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Model comparison

Claude Fable 5 vs GPT-5.6 Sol

Anthropic against OpenAI, compared on context, price, and attributed benchmark results.

Recorded profile verification October 1, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

Anthropic

Claude Fable 5

Frontier

vs

OpenAI

GPT-5.6 Sol

Frontier

AI model capability comparison
SpecificationClaude Fable 5GPT-5.6 Sol
ProviderAnthropicOpenAI
TierFrontierFrontier
Context window1MWinner: 1.05M
Max output128K128K
Input / 1M tokens$10Winner: $4
Output / 1M tokens$50Winner: $20
WeightsClosedClosed
ParametersNot verifiedUnverifiedNot verifiedUnverified
Reasoning levelslow, medium, high, xhigh, maxnone, low, medium, high, xhigh, max
Modalitiestext, imagetext, image
API model idclaude-fable-5gpt-5.6-sol
ReleasedJune 9, 2026July 9, 2026
Terminal-Bench 2.1 · source date GPT-5.6 Sol: 2026-07-09Not verifiedUnverified88.8
GPQA Diamond · source date GPT-5.6 Sol: 2026-07-09Not verifiedUnverified94.6

Dates beside benchmark scores refer to the linked source’s publication or capture date unless that source explicitly states when it measured the result. A shared URL alone does not establish comparable runs; unverified setups are marked. Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

  • Source date2026-07-09
    OpenAI — GPT-5.6 evals table (vendor)

    Graduate-level science reasoning: multiple-choice questions written by domain PhDs.

    Comparable with caveatDo not treat a fixed two-point band as universal measurement uncertainty; it depends on run count and evaluation setup. Chain-of-thought, prompt, and tool policy must match. The small pool limits fine-grained conclusions, and frontier scores can be near ceiling; Artificial Analysis dropped it from its Intelligence Index in v4.3.

  • Source date2026-07-09
    OpenAI — GPT-5.6 evals table (vendor; Ultra multi-agent config: 91.9)

    Agentic terminal work: multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNot comparable with Terminal-Bench 3.0 or 4.0 (different task sets) or v1; harness configuration (container, time limits) also shifts results.

Pricing tiers

Claude Fable 5: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high. Reliable knowledge cutoff Jan 2026; retirement not sooner than June 9, 2027. Access was suspended June 12 and restored July 1, 2026.

GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026.

FrontierRecord checked October 1, 2026

Claude Fable 5

Claude Fable 5 is Anthropic's June 2026 long-running-agent model, now 'Active (legacy)' behind Fable 5.1 at the same $10/$50 price.

Best for

  • Long-running agents
  • Frontier reasoning
  • Enterprise work

Watch out

Superseded: Fable 5.1 has the same base input/output prices and lower cache-read pricing ($0.25 vs $1 per million tokens). Savings depend on eligible cached requests; evaluate the successor against your pinned workloads.

FrontierRecord checked October 1, 2026

GPT-5.6 Sol

GPT-5.6 Sol was OpenAI's GPT-5.6 flagship for complex reasoning and coding with a 1.05M-token context — superseded on 2026-09-22 by GPT-6 Sol at half the price.

Best for

  • Complex reasoning
  • Agentic coding
  • Hard knowledge work

Watch out

GPT-6.1 Sol is the newer Sol option at $2/$10 Standard. GPT-5.6 Sol remains listed; its $4/$20 price is promotional. Max effort can increase token use, and Ultra is a multi-agent configuration rather than a separate reasoning.effort value.

When the cheaper one wins

GPT-5.6 Sol is cheaper on output at $20 per million tokens against $50 for Claude Fable 5 — about 2.5×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. On DeepSWE 1.1, GPT-5.6 Sol is 72.7% Pass@1 at $8.39/task versus Claude Fable 5 at 69.9% / $13.41/task. This compares standard short-context token rates, not total cost per accepted task. Include input, cache, context tiers, schedules, retries and review in your pilot.

Run the model picker

Evidence confidence: Medium

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • No directly aligned benchmark setup — No benchmark has matching cited sources, source dates, units, effort and recorded run details on both models.
  • Verified within the last 90 days — Older of the two catalog checks was 25 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Claude Fable 5 · GPT-5.6 Sol

Common questions

Claude Fable 5 vs GPT-5.6 Sol

Answered from the verified figures on this page rather than general guidance.

Is Claude Fable 5 or GPT-5.6 Sol cheaper for input?
GPT-5.6 Sol is cheaper at $4 per million input tokens, against $10 for Claude Fable 5 — roughly 2.5× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Fable 5: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high. Reliable knowledge cutoff Jan 2026; retirement not sooner than June 9, 2027. Access was suspended June 12 and restored July 1, 2026. GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026.
Is Claude Fable 5 or GPT-5.6 Sol cheaper for output?
GPT-5.6 Sol is cheaper at $20 per million output tokens, against $50 for Claude Fable 5 — roughly 2.5× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Fable 5: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high. Reliable knowledge cutoff Jan 2026; retirement not sooner than June 9, 2027. Access was suspended June 12 and restored July 1, 2026. GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026.
Which has the larger context window, Claude Fable 5 or GPT-5.6 Sol?
GPT-5.6 Sol accepts 1.05M tokens against 1M for Claude Fable 5. This only matters if you routinely send very long documents or large codebases.
Do Claude Fable 5 and GPT-5.6 Sol support the same reasoning levels?
Claude Fable 5 exposes low, medium, high, xhigh, max, while GPT-5.6 Sol exposes none, low, medium, high, xhigh, max.
Should I use Claude Fable 5 or GPT-5.6 Sol?
Both are classified in our frontier tier; this editorial grouping does not imply equal capability. Claude Fable 5 is a candidate for long-running agents; GPT-5.6 Sol is a candidate for complex reasoning. Compare accuracy, tool reliability, latency and cost on representative tasks.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: GPT-5.6 Sol costs $4 per 1M tokens versus $10 for Claude Fable 5 — a 2.5x difference at the headline tier.
  • Context: GPT-5.6 Sol takes 1.05M against 1M for Claude Fable 5 — only decisive if your prompts approach the smaller window.
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