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Grok 4 Fast

Grok 4 Fast is an AI model from xAI.

Publisher
xAI
Family
Grok
Input
Output
License
proprietary
Released
19 Sep 2025

Cite

Notes

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Attribution

Benchmark scores
AAprime-hubVals AI
Attribution policy →
Weights
Closed
API only
Input
$0.20
/1M tok
Output
$0.50
/1M tok
Blended
$0.28
#299/ 499/1M · 3:1
Speed
0
#103/ 498tok/s

Price & speed via Artificial Analysis · ranked across tracked models

Reasoning effortIndexSpeed
Reasoning17.90 t/s
Non-reasoning11.10 t/s

Intelligence Index per reasoning-effort setting, via Artificial Analysis · pricing identical across tiers

Reported on 20 evals across 11 domains - best 89.7% on AIME 2025: Problems from the American Invitational Mathematics Examination · #24 of 205

Reported eval scores

20
Hanabi12.9
Hanabi12.9
Text Quests18.3
LiveCodeBench83.2
MMLU-Pro85
Humanity's Last Exam (HLE)19.1
TaxEval v275.7
CorpFin v266.9
MortgageTax42.1
AIME 2025: Problems from the American Invitational Mathematics Examination89.7
GPQA Diamond84.7
SciCode44.2
τ²-bench (Tau²-bench)65.8
Terminal-Bench (Hard)18.9
IFBench50.5
MedScribe81.6
MedCode37.4
SAGE29.8
Vibe Code Bench v1.10