ZMIME
Comparison · 3 models · Updated Oct 4, 2026

Claude Opus 4.5 vs Claude Opus 4.1 vs GPT-5.1

GPT-5.1 comes out ahead, 60 to 55 and 49 on our weighted score, and it is the cheaper option too.

  1. 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

  2. Anthropic

    Claude Opus 4.1

    Released Aug 5, 2025

    49/100
    • ECI144.1
    • Price$15.00 / $75.00
    • Context200K
    Full specs Remove Claude Opus 4.1
  3. 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
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) and Claude Opus 4.1 (49). 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 · Claude Opus 4.1 144.1
  • Lowest priceGPT-5.1GPT-5.1 $3.44 · Claude Opus 4.5 $10.00 · Claude Opus 4.1 $30.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.1GPT-5.1 400,000 · Claude Opus 4.5 200,000 · Claude Opus 4.1 200,000 tokens
  • Widest inputsClaude Opus 4.5 and Claude Opus 4.1Claude Opus 4.5: Text, Images, PDFs · Claude Opus 4.1: Text, Images, PDFs · GPT-5.1: Text, Images
  • Self-hostingNo open weightsAll three are available only through APIs
How the score is built
MeasureWeightClaude Opus 4.5Claude Opus 4.1GPT-5.1
CapabilityCapabilities Index (ECI)50%787178
Price25%2024
Inputs & features15%807070
Context window10%323244
Overall100%55/10049/10060/100
02 — Side by side

Every spec in one table

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

Claude Opus 4.5 vs Claude Opus 4.1 vs GPT-5.1 specifications side by side
SpecificationClaude Opus 4.5AnthropicClaude Opus 4.1AnthropicGPT-5.1OpenAI
Capability
Capabilities Index (ECI)150.1 (best)144.1149.7
ECI rank#48 of 148 (best)#81 of 148#52 of 148
GPQA DiamondGraduate-level science questions86.1%77.3%87.6% (best)
FrontierMath Tiers 1–3Research-level mathematics34.4% (best)12.6%—
OTIS Mock AIME 2024–2025Competition mathematics86.1%68.9%88.6% (best)
SWE-bench VerifiedFixing real GitHub issues76.7% (best)73.4%68.0%
SimpleQA VerifiedShort factual questions45.7%—48.0% (best)
Price per million tokens
Input$5.00$15.00$1.25 (best)
Output$25.00$75.00$10.00 (best)
Cached input$0.50—$0.125 (best)
Blended (3:1)$10.00$30.00$3.44 (best)
Long-context rateSame rateSame rateSame rate
Price sourceOfficial Anthropic APIMedian of 14 providersOfficial OpenAI API
Limits
Context window200,000 tokens200,000 tokens400,000 tokens (best)
Max output64,000 tokens32,000 tokens128,000 tokens (best)
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsYesYesNo
AudioNoNoNo
VideoNoNoNo
ReasoningYeslow · medium · highYesYeslow · medium · high
Tool callingYesYesYes
Structured outputYesNoYes
Availability
WeightsProprietaryProprietaryProprietary
API model IDclaude-opus-4-5—gpt-5.1
API providers28 (best)1421
ReleasedNov 24, 2025Aug 5, 2025Nov 13, 2025
Knowledge cutoffMay 2025Mar 31, 2025Sep 30, 2024
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 Opus 4.5$100.00
  • Claude Opus 4.1$300.00
  • GPT-5.1$32.50
04 — Questions

Which should you choose?

Which is better: Claude Opus 4.5, Claude Opus 4.1 or GPT-5.1?

GPT-5.1 is the better all-round choice, scoring 60/100 against Claude Opus 4.5 (55) and Claude Opus 4.1 (49). 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, Claude Opus 4.5, Claude Opus 4.1 or GPT-5.1?

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); Claude Opus 4.1 costs $15.00 input / $75.00 output per million tokens (median across 14 API providers). 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) and $30.00 for Claude Opus 4.1 (8.7× 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), GPT-5.1 149.7 (#52 of 148) and Claude Opus 4.1 144.1 (#81 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%, Claude Opus 4.1 77.3%; OTIS Mock AIME 2024–2025 — GPT-5.1 88.6%, Claude Opus 4.5 86.1%, Claude Opus 4.1 68.9%; SWE-bench Verified — Claude Opus 4.5 76.7%, Claude Opus 4.1 73.4%, GPT-5.1 68.0%.

Which is better for coding?

Claude Opus 4.5 resolves more real GitHub issues on SWE-bench Verified: Claude Opus 4.5 76.7%, Claude Opus 4.1 73.4% and GPT-5.1 68.0%. All three 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 and 200,000 for Claude Opus 4.1. Maximum output per response: Claude Opus 4.5 up to 64,000, Claude Opus 4.1 up to 32,000, GPT-5.1 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Opus 4.5 accepts text, images and PDFs; Claude Opus 4.1 accepts text, images and PDFs; GPT-5.1 accepts text and images. Claude Opus 4.5 handles the widest range of inputs.

Are any of these open source?

No. Claude Opus 4.5, Claude Opus 4.1 and GPT-5.1 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; Claude Opus 4.1 came out Aug 5, 2025. Knowledge cutoff: Claude Opus 4.5 May 2025, Claude Opus 4.1 Mar 31, 2025, GPT-5.1 Sep 30, 2024.

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

Related comparisons