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Comparison · 2 models · Updated Oct 4, 2026

Claude Fable 5.1 vs GPT-5.6 Sol

Too close to call on our weighted score (Claude Fable 5.1 66, GPT-5.6 Sol 66). The right pick depends on what you value most.

  1. Anthropic

    Claude Fable 5.1

    Released Sep 1, 2026

    66/100
    • ECI164.8
    • Price$10.00 / $50.00
    • Context1M
    Full specs Remove Claude Fable 5.1

  2. OpenAI

    GPT-5.6 Sol

    Released Jul 9, 2026

    66/100
    • ECI161.8
    • Price$4.00 / $20.00
    • Context1.05M
    Full specs Remove GPT-5.6 Sol

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Too close to call

It is close. Our weighted score puts them within a point (Claude Fable 5.1 66/100, GPT-5.6 Sol 66/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, GPT-5.6 Sol on price and GPT-5.6 Sol for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Fable 5.1Capabilities Index (ECI): Claude Fable 5.1 164.8 · GPT-5.6 Sol 161.8
  • Lowest priceGPT-5.6 SolGPT-5.6 Sol $8.00 · Claude Fable 5.1 $20.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.6 SolGPT-5.6 Sol 1,050,000 · Claude Fable 5.1 1,000,000 tokens
  • Widest inputsSame inputsClaude Fable 5.1: Text, Images, PDFs · GPT-5.6 Sol: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Fable 5.1GPT-5.6 Sol
CapabilityCapabilities Index (ECI)50%9793
Price25%07
Inputs & features15%8080
Context window10%6061
Overall100%66/10066/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Claude Fable 5.1 vs GPT-5.6 Sol specifications side by side
SpecificationClaude Fable 5.1AnthropicGPT-5.6 SolOpenAI
Capability
Capabilities Index (ECI)164.8 (best)161.8
ECI rank#4 of 148 (best)#8 of 148
GPQA DiamondGraduate-level science questions—93.5%
FrontierMath Tiers 1–3Research-level mathematics90.2% (best)89.1%
OTIS Mock AIME 2024–2025Competition mathematics100%100%
SimpleQA VerifiedShort factual questions70.8% (best)69.7%
Price per million tokens
Input$10.00$4.00 (best)
Output$50.00$20.00 (best)
Cached input$0.25 (best)$0.40
Blended (3:1)$20.00$8.00 (best)
Long-context rateSame rateOver 272K: $8.00 / $30.00
Price sourceOfficial Anthropic APIOfficial OpenAI API
Limits
Context window1,000,000 tokens1,050,000 tokens (best)
Max output128,000 tokens128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhigh · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDclaude-fable-5-1gpt-5.6-sol
API providers2940 (best)
ReleasedSep 1, 2026Jul 9, 2026
Knowledge cutoffJun 2026Feb 16, 2026
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Claude Fable 5.1$200.00
  • GPT-5.6 Sol$80.00
04 — Questions

Which should you choose?

Which is better: Claude Fable 5.1 or GPT-5.6 Sol?

It is close. Our weighted score puts them within a point (Claude Fable 5.1 66/100, GPT-5.6 Sol 66/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, GPT-5.6 Sol on price and GPT-5.6 Sol for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Fable 5.1 or GPT-5.6 Sol?

GPT-5.6 Sol is cheaper at $4.00 input / $20.00 output per million tokens (official OpenAI API price). Claude Fable 5.1 costs $10.00 input / $50.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $8.00 per million tokens for GPT-5.6 Sol versus $20.00 for Claude Fable 5.1 (2.5× as much).

Which scores higher on benchmarks?

Claude Fable 5.1 scores higher on the Capabilities Index (ECI): Claude Fable 5.1 164.8 (#4 of 148) and GPT-5.6 Sol 161.8 (#8 of 148). The confidence ranges of the top two overlap (161.8–169.1 vs 159.3–165.3), so treat the gap as small. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5.1 90.2%, GPT-5.6 Sol 89.1%; OTIS Mock AIME 2024–2025 — Claude Fable 5.1 100%, GPT-5.6 Sol 100%; SimpleQA Verified — Claude Fable 5.1 70.8%, GPT-5.6 Sol 69.7%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Fable 5.1 and GPT-5.6 Sol yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5.1 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.6 Sol has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Fable 5.1. Maximum output per response: Claude Fable 5.1 up to 128,000, GPT-5.6 Sol up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Fable 5.1 accepts text, images and PDFs; GPT-5.6 Sol accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Fable 5.1 and GPT-5.6 Sol are proprietary and only available through APIs and apps.

Which is newer?

Claude Fable 5.1 is the newest, released Sep 1, 2026. GPT-5.6 Sol came out Jul 9, 2026. Knowledge cutoff: Claude Fable 5.1 Jun 2026, GPT-5.6 Sol Feb 16, 2026.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

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