ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GPT-5.1 vs Grok 4.3

Grok 4.3 comes out ahead, 67 to 60 on our weighted score, and it is the cheaper option too.

  1. 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. Our pick

    xAI

    Grok 4.3

    Released Apr 17, 2026

    67/100
    • ECI149.2
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.3

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Grok 4.3 is our pick

Grok 4.3 is the better all-round choice, scoring 67/100 against GPT-5.1 (60). It leads on price, inputs & features and 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 · Grok 4.3 149.2
  • Lowest priceGrok 4.3Grok 4.3 $1.56 · GPT-5.1 $3.44 per 1M tokens (3:1 blend)
  • Longest contextGrok 4.3Grok 4.3 1,000,000 · GPT-5.1 400,000 tokens
  • Widest inputsGrok 4.3GPT-5.1: Text, Images · Grok 4.3: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.1Grok 4.3
CapabilityCapabilities Index (ECI)50%7877
Price25%2441
Inputs & features15%7080
Context window10%4460
Overall100%60/10067/100
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 Grok 4.3 specifications side by side
SpecificationGPT-5.1OpenAIGrok 4.3xAI
Capability
Capabilities Index (ECI)149.7 (best)149.2
ECI rank#52 of 148 (best)#55 of 148
GPQA DiamondGraduate-level science questions87.6%88.8% (best)
FrontierMath Tiers 1–3Research-level mathematics—42.8%
OTIS Mock AIME 2024–2025Competition mathematics88.6%93.3% (best)
SWE-bench VerifiedFixing real GitHub issues68.0%—
SimpleQA VerifiedShort factual questions48.0% (best)33.2%
Price per million tokens
Input$1.25$1.25
Output$10.00$2.50 (best)
Cached input$0.125 (best)$0.20
Blended (3:1)$3.44$1.56 (best)
Long-context rateSame rateOver 200K: $2.50 / $5.00
Price sourceOfficial OpenAI APIOfficial xAI API
Limits
Context window400,000 tokens1,000,000 tokens (best)
Max output128,000 tokens (best)30,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · highYeslow · medium · high
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-5.1grok-4.3
API providers2127 (best)
ReleasedNov 13, 2025Apr 17, 2026
Knowledge cutoffSep 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$32.50
  • Grok 4.3$17.50
04 — Questions

Which should you choose?

Which is better: GPT-5.1 or Grok 4.3?

Grok 4.3 is the better all-round choice, scoring 67/100 against GPT-5.1 (60). It leads on price, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5.1 or Grok 4.3?

Grok 4.3 is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). GPT-5.1 costs $1.25 input / $10.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.3 versus $3.44 for GPT-5.1 (2.2× 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 Grok 4.3 149.2 (#55 of 148). The confidence ranges of the top two overlap (148.3–151.1 vs 147.6–150.8), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.3 88.8%, GPT-5.1 87.6%; OTIS Mock AIME 2024–2025 — Grok 4.3 93.3%, GPT-5.1 88.6%; SimpleQA Verified — GPT-5.1 48.0%, Grok 4.3 33.2%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.3 yet, so there is no like-for-like coding score. On overall capability, GPT-5.1 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

Grok 4.3 has the largest context window at 1,000,000 tokens, against 400,000 for GPT-5.1. Maximum output per response: GPT-5.1 up to 128,000, Grok 4.3 up to 30,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.1 accepts text and images; Grok 4.3 accepts text, images and PDFs. Grok 4.3 handles the widest range of inputs.

Are any of these open source?

No. GPT-5.1 and Grok 4.3 are proprietary and only available through APIs and apps.

Which is newer?

Grok 4.3 is the newest, released Apr 17, 2026. GPT-5.1 came out Nov 13, 2025. Knowledge cutoff: 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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