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Comparison · 3 models · Updated Oct 4, 2026

GPT-5 Pro vs Claude Fable 5 vs Claude Opus 4.5

Claude Fable 5 comes out ahead, 65 to 55 and 54 on our weighted score, though Claude Opus 4.5 is 2× cheaper per token.

  1. OpenAI

    GPT-5 Pro

    Released Oct 6, 2025

    54/100
    • ECI150.3
    • Price$15.00 / $120.00
    • Context400K
    Full specs Remove GPT-5 Pro
  2. Our pick

    Anthropic

    Claude Fable 5

    Released Jun 9, 2026

    65/100
    • ECI162.2
    • Price$10.00 / $50.00
    • Context1M
    Full specs Remove Claude Fable 5

  3. Anthropic

    Claude Opus 4.5

    Released Nov 24, 2025

    55/100
    • ECI150.1
    • Price$5.00 / $25.00
    • Context200K
    Full specs Remove Claude Opus 4.5
01 — Verdict

Claude Fable 5 is our pick

Claude Fable 5 is the better all-round choice, scoring 65/100 against Claude Opus 4.5 (55) and GPT-5 Pro (54). It leads on capability and context window. Claude Opus 4.5 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Fable 5Capabilities Index (ECI): Claude Fable 5 162.2 · GPT-5 Pro 150.3 · Claude Opus 4.5 150.1
  • Lowest priceClaude Opus 4.5Claude Opus 4.5 $10.00 · Claude Fable 5 $20.00 · GPT-5 Pro $41.25 per 1M tokens (3:1 blend)
  • Longest contextClaude Fable 5Claude Fable 5 1,000,000 · GPT-5 Pro 400,000 · Claude Opus 4.5 200,000 tokens
  • Widest inputsClaude Fable 5 and Claude Opus 4.5GPT-5 Pro: Text, Images · Claude Fable 5: Text, Images, PDFs · Claude Opus 4.5: Text, Images, PDFs
  • Self-hostingNo open weightsAll three are available only through APIs
How the score is built
MeasureWeightGPT-5 ProClaude Fable 5Claude Opus 4.5
CapabilityCapabilities Index (ECI)50%789478
Price25%002
Inputs & features15%708080
Context window10%446032
Overall100%54/10065/10055/100
02 — Side by side

Every spec in one table

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

GPT-5 Pro vs Claude Fable 5 vs Claude Opus 4.5 specifications side by side
SpecificationGPT-5 ProOpenAIClaude Fable 5AnthropicClaude Opus 4.5Anthropic
Capability
Capabilities Index (ECI)150.3162.2 (best)150.1
ECI rank#46 of 148#7 of 148 (best)#48 of 148
GPQA DiamondGraduate-level science questions—85.9%86.1% (best)
FrontierMath Tiers 1–3Research-level mathematics55.8%87.0% (best)34.4%
OTIS Mock AIME 2024–2025Competition mathematics—100% (best)86.1%
SWE-bench VerifiedFixing real GitHub issues——76.7%
SimpleQA VerifiedShort factual questions—70.7% (best)45.7%
Price per million tokens
Input$15.00$10.00$5.00 (best)
Output$120.00$50.00$25.00 (best)
Cached input—$1.00$0.50 (best)
Blended (3:1)$41.25$20.00$10.00 (best)
Long-context rateSame rateSame rateSame rate
Price sourceOfficial OpenAI APIOfficial Anthropic APIOfficial Anthropic API
Limits
Context window400,000 tokens1,000,000 tokens (best)200,000 tokens
Max output272,000 tokens (best)128,000 tokens64,000 tokens
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsNoYesYes
AudioNoNoNo
VideoNoNoNo
ReasoningYeshighYeslow · medium · high · xhigh · maxYeslow · medium · high
Tool callingYesYesYes
Structured outputYesYesYes
Availability
WeightsProprietaryProprietaryProprietary
API model IDgpt-5-proclaude-fable-5claude-opus-4-5
API providers1238 (best)28
ReleasedOct 6, 2025Jun 9, 2026Nov 24, 2025
Knowledge cutoffSep 30, 2024Jan 31, 2026May 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.

  • GPT-5 Pro$390.00
  • Claude Fable 5$200.00
  • Claude Opus 4.5$100.00
04 — Questions

Which should you choose?

Which is better: GPT-5 Pro, Claude Fable 5 or Claude Opus 4.5?

Claude Fable 5 is the better all-round choice, scoring 65/100 against Claude Opus 4.5 (55) and GPT-5 Pro (54). It leads on capability and context window. Claude Opus 4.5 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5 Pro, Claude Fable 5 or Claude Opus 4.5?

Claude Opus 4.5 is cheaper at $5.00 input / $25.00 output per million tokens (official Anthropic API price). Claude Fable 5 costs $10.00 input / $50.00 output per million tokens (official Anthropic API price); GPT-5 Pro costs $15.00 input / $120.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $10.00 per million tokens for Claude Opus 4.5 versus $20.00 for Claude Fable 5 (2× as much) and $41.25 for GPT-5 Pro (4.1× as much).

Which scores higher on benchmarks?

Claude Fable 5 scores higher on the Capabilities Index (ECI): Claude Fable 5 162.2 (#7 of 148), GPT-5 Pro 150.3 (#46 of 148) and Claude Opus 4.5 150.1 (#48 of 148). Their confidence ranges do not overlap (159.6–166.1 vs 148.5–152.8), so the gap is a real one. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5 87.0%, GPT-5 Pro 55.8%, Claude Opus 4.5 34.4%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5 Pro and Claude Fable 5 yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5 leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.

Which has the bigger context window?

Claude Fable 5 has the largest context window at 1,000,000 tokens, against 400,000 for GPT-5 Pro and 200,000 for Claude Opus 4.5. Maximum output per response: GPT-5 Pro up to 272,000, Claude Fable 5 up to 128,000, Claude Opus 4.5 up to 64,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5 Pro accepts text and images; Claude Fable 5 accepts text, images and PDFs; Claude Opus 4.5 accepts text, images and PDFs. Claude Fable 5 handles the widest range of inputs.

Are any of these open source?

No. GPT-5 Pro, Claude Fable 5 and Claude Opus 4.5 are proprietary and only available through APIs and apps.

Which is newer?

Claude Fable 5 is the newest, released Jun 9, 2026. Claude Opus 4.5 came out Nov 24, 2025; GPT-5 Pro came out Oct 6, 2025. Knowledge cutoff: GPT-5 Pro Sep 30, 2024, Claude Fable 5 Jan 31, 2026, Claude Opus 4.5 May 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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