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Comparison · 2 models · Updated Oct 4, 2026

GPT-5.1 Chat vs GPT-5 Chat

GPT-5.1 Chat comes out ahead, 38 to 34 on our weighted score.

  1. Our pick

    OpenAI

    GPT-5.1 Chat

    Released Nov 13, 2025

    38/100
    • ECI—
    • Price$1.25 / $10.00
    • Context128K
    Full specs Remove GPT-5.1 Chat

  2. OpenAI

    GPT-5 Chat

    Released Aug 7, 2025

    34/100
    • ECI—
    • Price$1.25 / $10.00
    • Context400K
    Full specs Remove GPT-5 Chat

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-5.1 Chat is our pick

GPT-5.1 Chat is the better all-round choice, scoring 38/100 against GPT-5 Chat (34). It leads on inputs & features. GPT-5 Chat wins on context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

  • CapabilityNot enough dataNo independent benchmark covers every model here yet
  • Lowest priceSame priceGPT-5.1 Chat $3.44 · GPT-5 Chat $3.44 per 1M tokens (3:1 blend)
  • Longest contextGPT-5 ChatGPT-5 Chat 400,000 · GPT-5.1 Chat 128,000 tokens
  • Widest inputsSame inputsGPT-5.1 Chat: Text, Images · GPT-5 Chat: Text, Images
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.1 ChatGPT-5 Chat
Price50%2424
Inputs & features30%7045
Context window20%2444
Overall100%38/10034/100

Left out because at least one model lacks the data: capability. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

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

GPT-5.1 Chat vs GPT-5 Chat specifications side by side
SpecificationGPT-5.1 ChatOpenAIGPT-5 ChatOpenAI
Capability
Capabilities Index (ECI)——
ECI rank——
Price per million tokens
Input$1.25$1.25
Output$10.00$10.00
Cached input——
Blended (3:1)$3.44$3.44
Long-context rateSame rateSame rate
Price sourceMedian of 2 providersMedian of 2 providers
Limits
Context window128,000 tokens400,000 tokens (best)
Max output16,384 tokens128,000 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoNo
AudioNoNo
VideoNoNo
ReasoningYesYes
Tool callingYesNo
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model ID——
API providers22
ReleasedNov 13, 2025Aug 7, 2025
Knowledge cutoffSep 30, 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-5.1 Chat$32.50
  • GPT-5 Chat$32.50
04 — Questions

Which should you choose?

Which is better: GPT-5.1 Chat or GPT-5 Chat?

GPT-5.1 Chat is the better all-round choice, scoring 38/100 against GPT-5 Chat (34). It leads on inputs & features. GPT-5 Chat wins on context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

Which is cheaper, GPT-5.1 Chat or GPT-5 Chat?

GPT-5.1 Chat and GPT-5 Chat cost the same: $1.25 input / $10.00 output per million tokens.

Which scores higher on benchmarks?

There is no independent benchmark that covers both models yet. GPT-5.1 Chat has not been scored yet and GPT-5 Chat has not been scored yet.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5.1 Chat and GPT-5 Chat yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Note that GPT-5 Chat does not support tool calling, which most coding agents need.

Which has the bigger context window?

GPT-5 Chat has the largest context window at 400,000 tokens, against 128,000 for GPT-5.1 Chat. Maximum output per response: GPT-5.1 Chat up to 16,384, GPT-5 Chat up to 128,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.1 Chat accepts text and images; GPT-5 Chat accepts text and images. They handle the same number of input types.

Are any of these open source?

No. GPT-5.1 Chat and GPT-5 Chat are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.1 Chat is the newest, released Nov 13, 2025. GPT-5 Chat came out Aug 7, 2025. Knowledge cutoff: GPT-5.1 Chat Sep 30, 2024, GPT-5 Chat 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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