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Comparison · 2 models · Updated Oct 4, 2026

GPT-4.1 vs GPT-5.1

GPT-5.1 comes out ahead, 60 to 53 on our weighted score, and it is the cheaper option too.

  1. OpenAI

    GPT-4.1

    Released Apr 14, 2025

    53/100
    • ECI136.8
    • Price$2.00 / $8.00
    • Context1.05M
    Full specs Remove GPT-4.1
  2. 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

  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 GPT-4.1 (53). It leads on capability. GPT-4.1 wins on context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGPT-5.1Capabilities Index (ECI): GPT-5.1 149.7 · GPT-4.1 136.8
  • Lowest priceGPT-5.1GPT-5.1 $3.44 · GPT-4.1 $3.50 per 1M tokens (3:1 blend)
  • Longest contextGPT-4.1GPT-4.1 1,047,576 · GPT-5.1 400,000 tokens
  • Widest inputsGPT-4.1GPT-4.1: Text, Images, PDFs · GPT-5.1: Text, Images
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-4.1GPT-5.1
CapabilityCapabilities Index (ECI)50%6178
Price25%2424
Inputs & features15%7070
Context window10%6144
Overall100%53/10060/100
02 — Side by side

Every spec in one table

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

GPT-4.1 vs GPT-5.1 specifications side by side
SpecificationGPT-4.1OpenAIGPT-5.1OpenAI
Capability
Capabilities Index (ECI)136.8149.7 (best)
ECI rank#111 of 148#52 of 148 (best)
GPQA DiamondGraduate-level science questions66.9%87.6% (best)
FrontierMath Tiers 1–3Research-level mathematics6.0%—
OTIS Mock AIME 2024–2025Competition mathematics38.3%88.6% (best)
SWE-bench VerifiedFixing real GitHub issues48.5%68.0% (best)
SimpleQA VerifiedShort factual questions31.1%48.0% (best)
Price per million tokens
Input$2.00$1.25 (best)
Output$8.00 (best)$10.00
Cached input$0.50$0.125 (best)
Blended (3:1)$3.50$3.44 (best)
Long-context rateSame rateSame rate
Price sourceOfficial OpenAI APIOfficial OpenAI API
Limits
Context window1,047,576 tokens (best)400,000 tokens
Max output32,768 tokens128,000 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesNo
AudioNoNo
VideoNoNo
ReasoningNoYeslow · medium · high
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-4.1gpt-5.1
API providers25 (best)21
ReleasedApr 14, 2025Nov 13, 2025
Knowledge cutoffApr 2024Sep 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.

  • GPT-4.1$36.00
  • GPT-5.1$32.50
04 — Questions

Which should you choose?

Which is better: GPT-4.1 or GPT-5.1?

GPT-5.1 is the better all-round choice, scoring 60/100 against GPT-4.1 (53). It leads on capability. GPT-4.1 wins on context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-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). GPT-4.1 costs $2.00 input / $8.00 output per million tokens (official OpenAI 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 $3.50 for GPT-4.1 (1× as much).

Which scores higher on benchmarks?

GPT-5.1 scores higher on the Capabilities Index (ECI): GPT-5.1 149.7 (#52 of 148) and GPT-4.1 136.8 (#111 of 148). Their confidence ranges do not overlap (148.3–151.1 vs 133.6–138.4), so the gap is a real one. On individual benchmarks: GPQA Diamond — GPT-5.1 87.6%, GPT-4.1 66.9%; OTIS Mock AIME 2024–2025 — GPT-5.1 88.6%, GPT-4.1 38.3%; SWE-bench Verified — GPT-5.1 68.0%, GPT-4.1 48.5%; SimpleQA Verified — GPT-5.1 48.0%, GPT-4.1 31.1%.

Which is better for coding?

GPT-5.1 resolves more real GitHub issues on SWE-bench Verified: GPT-5.1 68.0% and GPT-4.1 48.5%. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-4.1 has the largest context window at 1,047,576 tokens, against 400,000 for GPT-5.1. Maximum output per response: GPT-4.1 up to 32,768, GPT-5.1 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

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

Are any of these open source?

No. GPT-4.1 and GPT-5.1 are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.1 is the newest, released Nov 13, 2025. GPT-4.1 came out Apr 14, 2025. Knowledge cutoff: GPT-4.1 Apr 2024, 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

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