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Comparison · 2 models · Updated Oct 4, 2026

Claude Fable 5.1 vs GPT-5.4

Too close to call on our weighted score (Claude Fable 5.1 66, GPT-5.4 65). 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-5.4

    Released Mar 5, 2026

    65/100
    • ECI156.9
    • Price$2.50 / $15.00
    • Context1.05M
    Full specs Remove GPT-5.4

  3. Add a model

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 1 points (Claude Fable 5.1 66/100, GPT-5.4 65/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, GPT-5.4 on price and GPT-5.4 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-5.4 156.9
  • Lowest priceGPT-5.4GPT-5.4 $5.63 · Claude Fable 5.1 $20.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.4GPT-5.4 1,050,000 · Claude Fable 5.1 1,000,000 tokens
  • Widest inputsSame inputsClaude Fable 5.1: Text, Images, PDFs · GPT-5.4: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Fable 5.1GPT-5.4
CapabilityCapabilities Index (ECI)50%9787
Price25%014
Inputs & features15%8080
Context window10%6061
Overall100%66/10065/100
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-5.4 specifications side by side
SpecificationClaude Fable 5.1AnthropicGPT-5.4OpenAI
Capability
Capabilities Index (ECI)164.8 (best)156.9
ECI rank#4 of 148 (best)#16 of 148
GPQA DiamondGraduate-level science questions—93.3%
FrontierMath Tiers 1–3Research-level mathematics90.2% (best)78.6%
OTIS Mock AIME 2024–2025Competition mathematics100% (best)97.8%
SWE-bench VerifiedFixing real GitHub issues—76.9%
SimpleQA VerifiedShort factual questions70.8% (best)45.1%
Price per million tokens
Input$10.00$2.50 (best)
Output$50.00$15.00 (best)
Cached input$0.25$0.25
Blended (3:1)$20.00$5.63 (best)
Long-context rateSame rateOver 272K: $5.00 / $22.50
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
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDclaude-fable-5-1gpt-5.4
API providers2936 (best)
ReleasedSep 1, 2026Mar 5, 2026
Knowledge cutoffJun 2026Aug 31, 2025
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-5.4$55.00
04 — Questions

Which should you choose?

Which is better: Claude Fable 5.1 or GPT-5.4?

It is close. Our weighted score puts them within 1 points (Claude Fable 5.1 66/100, GPT-5.4 65/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, GPT-5.4 on price and GPT-5.4 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-5.4?

GPT-5.4 is cheaper at $2.50 input / $15.00 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 $5.63 per million tokens for GPT-5.4 versus $20.00 for Claude Fable 5.1 (3.6× 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-5.4 156.9 (#16 of 148). Their confidence ranges do not overlap (161.8–169.1 vs 154.9–159.1), so the gap is a real one. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5.1 90.2%, GPT-5.4 78.6%; OTIS Mock AIME 2024–2025 — Claude Fable 5.1 100%, GPT-5.4 97.8%; SimpleQA Verified — Claude Fable 5.1 70.8%, GPT-5.4 45.1%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Fable 5.1 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-5.4 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-5.4 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Fable 5.1 accepts text, images and PDFs; GPT-5.4 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-5.4 are proprietary and only available through APIs and apps.

Which is newer?

Claude Fable 5.1 is the newest, released Sep 1, 2026. GPT-5.4 came out Mar 5, 2026. Knowledge cutoff: Claude Fable 5.1 Jun 2026, GPT-5.4 Aug 31, 2025.

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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