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grok-4-fast

Grok 4 Fast is xAI’s proprietary AI model, released Sep 19, 2025.

Context
Input
/ 1M
Output
/ 1M
Released
Sep 19, 2025
Modalities

Benchmarks

Scores on standardized evaluations. Higher is better — and rank shows where Grok 4 Fast lands among all models tracked on Model Beat.

39.0
Intelligence Index
Epoch AI
39th percentile of tracked models
42.0
Coding Index
Epoch AI
42nd percentile of tracked models
23.0
Agentic Index
Epoch AI
23rd percentile of tracked models

Reasoning

6 evals
ARC-AGI48.5%

Abstract visual reasoning

ARC-AGI-25.3%

Harder abstract reasoning

GPQA Diamond84.7%

Graduate-level scientific reasoning

Humanity's Last Exam17.0%

Frontier of human expert knowledge

MMLU-Pro85.0%

Broad expert knowledge

WeirdML42.9%

Novel ML problem-solving

Coding

3 evals
LiveCodeBench83.2%

Contamination-free coding

SciCode44.2%

Scientific research coding

WebDev Arena1149

Human-rated web development

Math

1 evals
AIME 2024/202589.7%

Olympiad-qualifier math

Agentic & Tools

1 evals
τ²-bench65.8%

Tool-agent-user reliability

Compare Grok 4 Fast with

Frequently asked questions

What is Grok 4 Fast?

Grok 4 Fast is a Grok-family AI model, from xAI, released Sep 19, 2025.

Who created Grok 4 Fast?

Grok 4 Fast is an AI model developed by xAI, part of the Grok family, released Sep 19, 2025.

How does Grok 4 Fast perform on benchmarks?

On standardized evaluations tracked by Epoch AI, Grok 4 Fast scores 83.2% on LiveCodeBench, 85.0% on MMLU-Pro, 44.2% on SciCode.

Is Grok 4 Fast open source?

Grok 4 Fast is a proprietary model (API access), available through its provider's API rather than as a downloadable open-weight model.

Benchmark data from Epoch AI (CC BY) and Artificial Analysis; pricing, specs & descriptions from OpenRouter. Data updated Jul 30, 2026.