ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GPT-5.1 vs Claude Opus 4.5

GPT-5.1 comes out ahead, 60 to 55 on our weighted score, and it is the cheaper option too.

  1. Our pick

    OpenAI

    GPT-5.1

    Released Nov 13, 2025

    60/100
    • ECI149.7
    • Price$1.25 / $10.00
    • Context400K
    Full specs Remove GPT-5.1

  2. 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

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-5.1 is our pick

GPT-5.1 is the better all-round choice, scoring 60/100 against Claude Opus 4.5 (55). It leads on price and context window. Claude Opus 4.5 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Opus 4.5Capabilities Index (ECI): Claude Opus 4.5 150.1 · GPT-5.1 149.7
  • Lowest priceGPT-5.1GPT-5.1 $3.44 · Claude Opus 4.5 $10.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.1GPT-5.1 400,000 · Claude Opus 4.5 200,000 tokens
  • Widest inputsClaude Opus 4.5GPT-5.1: Text, Images · Claude Opus 4.5: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.1Claude Opus 4.5
CapabilityCapabilities Index (ECI)50%7878
Price25%242
Inputs & features15%7080
Context window10%4432
Overall100%60/10055/100
02 — Side by side

Every spec in one table

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

GPT-5.1 vs Claude Opus 4.5 specifications side by side
SpecificationGPT-5.1OpenAIClaude Opus 4.5Anthropic
Capability
Capabilities Index (ECI)149.7150.1 (best)
ECI rank#52 of 148#48 of 148 (best)
GPQA DiamondGraduate-level science questions87.6% (best)86.1%
FrontierMath Tiers 1–3Research-level mathematics—34.4%
OTIS Mock AIME 2024–2025Competition mathematics88.6% (best)86.1%
SWE-bench VerifiedFixing real GitHub issues68.0%76.7% (best)
SimpleQA VerifiedShort factual questions48.0% (best)45.7%
Price per million tokens
Input$1.25 (best)$5.00
Output$10.00 (best)$25.00
Cached input$0.125 (best)$0.50
Blended (3:1)$3.44 (best)$10.00
Long-context rateSame rateSame rate
Price sourceOfficial OpenAI APIOfficial Anthropic API
Limits
Context window400,000 tokens (best)200,000 tokens
Max output128,000 tokens (best)64,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · highYeslow · medium · high
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-5.1claude-opus-4-5
API providers2128 (best)
ReleasedNov 13, 2025Nov 24, 2025
Knowledge cutoffSep 30, 2024May 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-5.1$32.50
  • Claude Opus 4.5$100.00
04 — Questions

Which should you choose?

Which is better: GPT-5.1 or Claude Opus 4.5?

GPT-5.1 is the better all-round choice, scoring 60/100 against Claude Opus 4.5 (55). It leads on price and context window. Claude Opus 4.5 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5.1 or Claude Opus 4.5?

GPT-5.1 is cheaper at $1.25 input / $10.00 output per million tokens (official OpenAI API price). Claude Opus 4.5 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.44 per million tokens for GPT-5.1 versus $10.00 for Claude Opus 4.5 (2.9× as much).

Which scores higher on benchmarks?

Claude Opus 4.5 scores higher on the Capabilities Index (ECI): Claude Opus 4.5 150.1 (#48 of 148) and GPT-5.1 149.7 (#52 of 148). The confidence ranges of the top two overlap (147.9–153.0 vs 148.3–151.1), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-5.1 87.6%, Claude Opus 4.5 86.1%; OTIS Mock AIME 2024–2025 — GPT-5.1 88.6%, Claude Opus 4.5 86.1%; SWE-bench Verified — Claude Opus 4.5 76.7%, GPT-5.1 68.0%; SimpleQA Verified — GPT-5.1 48.0%, Claude Opus 4.5 45.7%.

Which is better for coding?

Claude Opus 4.5 resolves more real GitHub issues on SWE-bench Verified: Claude Opus 4.5 76.7% and GPT-5.1 68.0%. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.1 has the largest context window at 400,000 tokens, against 200,000 for Claude Opus 4.5. Maximum output per response: GPT-5.1 up to 128,000, Claude Opus 4.5 up to 64,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.1 accepts text and images; Claude Opus 4.5 accepts text, images and PDFs. Claude Opus 4.5 handles the widest range of inputs.

Are any of these open source?

No. GPT-5.1 and Claude Opus 4.5 are proprietary and only available through APIs and apps.

Which is newer?

Claude Opus 4.5 is the newest, released Nov 24, 2025. GPT-5.1 came out Nov 13, 2025. Knowledge cutoff: GPT-5.1 Sep 30, 2024, 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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