Compare Claude Opus 4.8 and GPT-5.6 Terra: Frontier Reasoning vs Enterprise Scale
Claude Opus 4.8 vs GPT-5.6 Terra: which should I use?
OpenAI GPT-5.6 Terra provides balanced mid-tier reasoning ($2.50/$15.00 per million tokens) with 1M context, while Claude Opus 4.8 delivers deep analytical reasoning and 500K context ($5.00/$25.00 per million tokens). Verified 2026-09-07.
Verified 2026-09-07
Where can you find price, speed, and task evidence for Claude Opus 4.8 and GPT-5.6 Terra?
Which tasks fit Claude Opus 4.8 and GPT-5.6 Terra?
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| Best fit | Complex, multi-step tasks where Fable 5’s premium isn’t justified. | Everyday production workloads that need strong quality without Sol-tier pricing. |
| Reasoning mode | Available | Available |
What does a Coding Agent workload cost with Claude Opus 4.8 and GPT-5.6 Terra?
Modeled for Coding Agent: 20,000 input + 2,000 output tokens per task, 1 turn. This is a workload model, not a provider quote.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| Coding Agent / task | $0.15 (modeled) | $0.08 (modeled) (winner) |
| Input / output rate | $5.00 / $25.00 per M | $2.50 / $15.00 per M |
How fast are Claude Opus 4.8 and GPT-5.6 Terra?
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| Measured throughput | 58 tokens/s | 78 tokens/s (winner) |
| Time to first token | 470 ms | 380 ms |
How compatible are Claude Opus 4.8 and GPT-5.6 Terra with APIs?
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| OpenAI SDK | Not drop-in | Usable |
| Request shape | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. | Canonical /chat/completions and /responses shape — every OpenAI-compatible provider on this site imitates it. |
| Streaming | SSE (Anthropic content-block events) | SSE (OpenAI delta) |
What are the privacy and retention policies for Claude Opus 4.8 and GPT-5.6 Terra?
Provider policy and residency facts from the verified provider registry. A missing retention policy is not treated as a guarantee.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| Provider says API data trains models | No | No |
| Published retention period | Unavailable | Unavailable |
| Data residency | Unavailable | US by default; EU data residency available on enterprise agreements |
How much effort does it take to migrate between Claude Opus 4.8 and GPT-5.6 Terra?
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | Claude Opus 4.8 | GPT-5.6 Terra |
|---|---|---|
| Move Claude Opus 4.8 → GPT-5.6 Terra | config; 3 breaking parameter differences | Target: GPT-5.6 Terra |
| Move GPT-5.6 Terra → Claude Opus 4.8 | Source: GPT-5.6 Terra | code-change; 8 breaking parameter differences |
| Why | Keep the `openai` SDK; change `baseURL` and the API key. | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. |
Batch 53 · exact pair cross-provider decision contributions. Surface verification: 2026-09-02. These three boards are server-rendered from frozen scenarios; assumptions and unavailable joins are not observations.
Exact pair boundary: requested models are claude-opus-4-8 and gpt-5.6-terra. Provider, pricing, task, and rate-limit pages remain fact owners.
Opus-to-Terra protocol delta compiler
Frozen Batch 53 scenario board. Formula / decision rule: migration_safe = required semantic mapped ∧ response parser validated ∧ tool/stream usage preserved; silent loss blocks Boundary: This compiler owns exact Opus-to-Terra protocol replacement, not a general migration tutorial.
| Frozen scenario / field ID | Joined fields and evidence | Output | State |
|---|---|---|---|
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r1system/developer instruction | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source=Anthropic Messages system; target=OpenAI Responses instructions; hosts/IDs=exact; prompt hash=proto-001; mapping=required | Require a prompt-equivalence probe before treating instruction fields as interchangeable. | CONDITIONAL — probe required |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r2adaptive reasoning | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source=thinking; target=reasoning effort; settings=exact; visible/hidden accounting=required; config hash=proto-002 | Unavailable — reasoning control and token accounting are not joined | UNAVAILABLE — control semantics unknown |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r3strict JSON | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source structured output; target JSON schema; schema hash=proto-003; parser/validation=required; result hash=missing | Unavailable — response shape and validator results are absent | UNAVAILABLE — schema join missing |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r4parallel tools | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source/target tool call IDs/order=required; tool schema=paired; side_effects=isolated; config hash=proto-004 | Unavailable — ordered tool trace and result association are missing | UNAVAILABLE — tool parity gap |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r5image input | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source modality=image; target modality=image; artifact hash=proto-005; media accounting=required; output reserve=declared | Unavailable — cross-provider media accounting and acceptance are unjoined | UNAVAILABLE — media join missing |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m1-r6streamed usage | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; stream event sequence=required; stop/usage fields=required; parser version=required; result hash=proto-006 | Unavailable — paired stream settlement and usage fields are absent | BLOCKED — usage semantics unknown |
Provenance: Batch 53 claude-opus-4-8-vs-gpt-5-6-terra; first-party source OpenAI Responses API; surface verification date 2026-09-02. Missing joins fail closed.
Effort-normalized replacement evidence ledger
Frozen Batch 53 scenario board. Formula / decision rule: comparable = same benchmark/version/effort/tools/judge/denominator; asymmetric evidence => no aggregate winner Boundary: A provider-only score or changed effort can inform a probe but cannot establish replacement quality.
| Frozen scenario / field ID | Joined fields and evidence | Output | State |
|---|---|---|---|
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r1shared benchmark/version | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; evaluation/version=required; Opus/Terra exact IDs; effort/tools=matched; judge/denominator=required; dates=required | Unavailable — shared paired benchmark row is not present | UNAVAILABLE — benchmark join missing |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r2different effort | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; evaluation/version=paired; Opus effort=high; Terra effort=medium; prompt hash=effort-002; tool policy=paired | Keep this row out of a model delta because effort changed. | NOT COMPARABLE — effort mismatch |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r3different tool access | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; benchmark/version=paired; Opus tools=enabled; Terra tools=none; schema/side_effects=changed; result hash=missing | Tool access is a confounder and blocks an aggregate replacement claim. | NOT COMPARABLE — tool mismatch |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r4provider-only row | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; source=first-party provider claim; exact model=one side; judge/denominator=missing; date=required | Use as contract context only; never fill the other model’s cell. | UNAVAILABLE — asymmetric source |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r5matched local canary | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; cohort hash=local-005; prompt/config/result hashes=paired; exact host/time=required; acceptance rubric=required | Unavailable — paired local raw outputs and telemetry are absent | HOLD — local evidence missing |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m2-r6missing Terra or Opus cell fixtures | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; evaluation/version/settings=partial; one model value=missing; denominator=partial; source/date=known | No aggregate winner is calculated with an empty pair cell. | UNAVAILABLE — asymmetric coverage |
Provenance: Batch 53 claude-opus-4-8-vs-gpt-5-6-terra; first-party source Anthropic Claude model documentation; surface verification date 2026-09-02. Missing joins fail closed.
Cross-provider replacement canary board
Frozen Batch 53 scenario board. Formula / decision rule: promote = sample floor ∧ quality/schema/tool/latency/token gates pass ∧ fallback ready; otherwise hold or rollback Boundary: Opus remains the live fallback until every critical cohort clears; launch benchmarks cannot promote Terra.
| Frozen scenario / field ID | Joined fields and evidence | Output | State |
|---|---|---|---|
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r1read-only analysis | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; cohort=analysis; prompt/config hashes=paired; rubric=declared; p95/token telemetry=required; fallback=Opus | Unavailable — paired observation is absent | HOLD — baseline retained |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r2coding patch | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; cohort=code; repository/artifact/test hashes=paired; schema=patch; side_effects=isolated; sample_floor=required | Unavailable — candidate patch acceptance and rollback artifact are missing | HOLD — coding gate |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r3strict extraction | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; cohort=extract; schema hash=paired; field floor=declared; parser result=required; output tokens=observed | Unavailable — paired field denominator is absent | HOLD — schema gate |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r4tool agent | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; cohort=agent; tool/event IDs=paired; attempt_cap=2; side_effect audit=required; reviewer=required | Unavailable — paired tool trace and reviewer outcome are missing | HOLD — tool gate |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r5400K context | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; input=400K; tokenizer/estimate owner=required; output/tool reserve=declared; citation/recall rubric=required | Unavailable — usable-context canary and accounting are unjoined | UNAVAILABLE — context gate |
batch53-claude-opus-4-8-vs-gpt-5-6-terra-m3-r6regression fixtures | pair=claude-opus-4-8 vs gpt-5.6-terra; surfaces=Anthropic Messages@api.anthropic.com / OpenAI Responses@api.openai.com; requested IDs=claude-opus-4-8,gpt-5.6-terra; effective IDs=claude-opus-4-8,gpt-5.6-terra; baseline=Opus exact ID; candidate=Terra exact ID; cohort/config hashes=paired; critical failures=zero; rollback=ready | Rollback to Opus on any critical regression; promote only after sample floor. | CONDITIONAL — release gate |
Provenance: Batch 53 claude-opus-4-8-vs-gpt-5-6-terra; first-party source OpenAI Responses API; surface verification date 2026-09-02. Missing joins fail closed.
Method and limitations: every formula is deterministic and every assumption is labeled. Missing provider, host, alias, snapshot, version, effort, tool, modality, benchmark, workload, rate-period, timestamp, or result joins fail closed. Run the claude-opus-4-8-vs-gpt-5-6-terra Batch 53 scenario →
Batch 65 · exact-pair decision contributions · verified 2026-09-07
Exact pair boundary: Anthropic / OpenAI; model endpoint, premier reasoning flagship vs mid-tier balanced workhorse, and pricing must join. Requested models are claude-opus-4-8 and gpt-5.6-terra. Provider, rate, pricing, and task pages remain fact owners.
Token pricing and 2x enterprise budget impact matrix
Frozen Batch 65 scenario board. Formula / deterministic rule: monthly_spend = calls * ((in_tokens * rate_in + out_tokens * rate_out) / 1M) Boundary: Owns base token tariff comparisons and workload expenditure modeling.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r110K enterprise coding queries | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=10K enterprise coding queries; workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 10K enterprise coding queries is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r250K automated pull request reviews | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=50K automated pull request reviews; workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 50K automated pull request reviews is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r3100K document analysis passes | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=100K document analysis passes; workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 100K document analysis passes is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r4prompt caching active (Opus 90% read / Terra 50% read) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=prompt caching active (Opus 90% read / Terra 50% read); workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — prompt caching active (Opus 90% read / Terra 50% read) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r5batch processing active (50% both) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=batch processing active (50% both); workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — batch processing active (50% both) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m1-r6unresolved pricing currency | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=unresolved pricing currency; workload; prompt tokens; completion tokens; Opus 4.8 spend; Terra spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unresolved pricing currency has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: Anthropic API pricing; verification date 2026-09-07. Missing or conflicting joins fail closed.
Context window saturation (500K vs 1M) capability gate
Frozen Batch 65 scenario board. Formula / deterministic rule: eligible = (context <= 500K ? Both : (context <= 1M ? Terra : Excluded)) Boundary: Owns context scaling and capability gating for large inputs.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r1short prompt (15K tokens) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=short prompt (15K tokens); context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — short prompt (15K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r2detailed legal contract (120K tokens) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=detailed legal contract (120K tokens); context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — detailed legal contract (120K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r3large monolithic codebase (500K boundary) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=large monolithic codebase (500K boundary); context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — large monolithic codebase (500K boundary) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r4massive enterprise monorepo (800K tokens) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=massive enterprise monorepo (800K tokens); context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — massive enterprise monorepo (800K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r51M full context saturation test | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=1M full context saturation test; context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 1M full context saturation test is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m2-r6unsupported payload encoding | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=unsupported payload encoding; context size; Opus 4.8 eligible; Terra eligible; Opus cost; Terra cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unsupported payload encoding has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: Anthropic Claude model documentation; verification date 2026-09-07. Missing or conflicting joins fail closed.
Dual-canary architectural cutover and consensus verification
Frozen Batch 65 scenario board. Formula / deterministic rule: canary_spend = dual_runs * (opus_cost + terra_cost); consensus determines production cutover Boundary: Owns dual-run evaluation framework across top frontier architectures.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r150 automated complex refactoring pull requests | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=50 automated complex refactoring pull requests; evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 50 automated complex refactoring pull requests is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r2200 architecture design proofs | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=200 architecture design proofs; evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 200 architecture design proofs is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r3500 comprehensive security reviews | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=500 comprehensive security reviews; evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 500 comprehensive security reviews is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r41K integration bug root-cause analyses | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=1K integration bug root-cause analyses; evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 1K integration bug root-cause analyses is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r5consensus agreement threshold (>95%) | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=consensus agreement threshold (>95%); evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — consensus agreement threshold (>95%) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-terra-m3-r6divergent architectural recommendation resolution | pair=claude-opus-4-8 vs gpt-5.6-terra; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-terra; scenario=divergent architectural recommendation resolution; evaluation workload; Opus 4.8 spend; Terra spend; dual-run budget; consensus rate; cutover status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — divergent architectural recommendation resolution is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
First-party provenance: OpenAI rate limits; verification date 2026-09-07. Missing or conflicting joins fail closed.
Method and limitations: formulas are deterministic; observed and assumed inputs are labeled; no missing provider, host, account, region, realm, alias, snapshot, revision, weight, artifact, control, tool, modality, workload, rate-period, timestamp, or result is transferred. Run the claude-opus-4-8-vs-gpt-5-6-terra Batch 65 scenario →
How do Claude Opus 4.8 and GPT-5.6 Terra compare on specs?
| Claude Opus 4.8 | GPT-5.6 Terra | |
|---|---|---|
| Price (input) | $5.00/M | $2.50/M ✓ |
| Price (output) | $25.00/M | $15.00/M ✓ |
| Blended price | $10.00/M | $5.63/M ✓ |
| Context window | 500,000 tokens | 1,000,000 tokens ✓ |
| Max output | 64,000 tokens | 128,000 tokens ✓ |
| Modalities | text, vision | text, vision |
| Reasoning mode | Yes | Yes |
| Released | 2026-04 | 2026-06 |
| Speed | 58 t/s | 78 t/s ✓ |
How much do Claude Opus 4.8 and GPT-5.6 Terra cost at scale?
| Tokens / month | Claude Opus 4.8 | GPT-5.6 Terra | Delta |
|---|---|---|---|
| 1,000,000 | $10.00 | $5.63 | $4.38 (1.8×) |
| 10,000,000 | $100.00 | $56.25 | $43.75 (1.8×) |
| 100,000,000 | $1000.00 | $562.50 | $437.50 (1.8×) |
Choose Claude Opus 4.8 if…
- ✓Elite coding and multi-step reasoning
- ✓Strong instruction following on ambiguous prompts
- ✓Extended-thinking mode
- ✓Complex, multi-step tasks where Fable 5’s premium isn’t justified.
Choose GPT-5.6 Terra if…
- ✓Balanced cost-to-intelligence ratio
- ✓Reasoning mode available on demand
- ✓Same 1M context as Sol
- ✓Everyday production workloads that need strong quality without Sol-tier pricing.
Run this exact matchup right now
Send the same prompt to Claude Opus 4.8 and GPT-5.6 Terra side by side and see the outputs yourself.
Try Claude Opus 4.8 vs GPT-5.6 Terra FreeWhat are common questions about Claude Opus 4.8 and GPT-5.6 Terra?
Is Claude Opus 4.8 cheaper than GPT-5.6 Terra?
GPT-5.6 Terra is cheaper, at $5.63 per million blended tokens vs $10.00 for Claude Opus 4.8.
Which has the bigger context window, Claude Opus 4.8 or GPT-5.6 Terra?
GPT-5.6 Terra has the larger context window: 1,000,000 tokens vs 500,000.
Can Claude Opus 4.8 replace GPT-5.6 Terra for coding?
Both are viable for coding. Elite coding and multi-step reasoning (Claude Opus 4.8) vs Balanced cost-to-intelligence ratio (GPT-5.6 Terra) — pick based on which strength matters more for your workload.
Which is faster, Claude Opus 4.8 or GPT-5.6 Terra?
GPT-5.6 Terra is faster: 78 t/s vs 58 t/s, measured on our speed benchmarks.
Neither of these? See Claude Opus 4.8 alternatives or GPT-5.6 Terra alternatives.
What related comparisons help choose between Claude Opus 4.8 and GPT-5.6 Terra?
Claude Opus 4.8 pricingGPT-5.6 Terra pricingvs Claude Opus 4vs DeepSeek V4 Provs Gemini 3.1 Provs Gemini 3.7 FlashPremium model tests
Pricing verified 2026-06-07. Specs verified 2026-08-14.