Grok 4 Fast
Sep 2025
Grok 4 FastCompare inon
Benchmarks of Grok 4 Fast43
BenchmarkByScoreRank
Overall1
Knowledge5
Reasoning4
Science2
Coding4
Agents1
Multimodal1
Writing17
Health & law3
Documents1
Legacy · saturated or no longer reported4
No benchmark matches
—per task?
not available via APIprice
—output speed?
2Mcontext
Rankingin non-thinking mode?
Retired models are left out of the current rankings.
Alternatives?
ModelScoreCostPer taskWhat changes
BetterGPT-6 Lunalow+95%—$0.005Context: 2M → 1.05M+4
OpenMiMo v2.6 Prothinking×4.2—$0.13Context: 2M → 1M+4BetterGPT-5.6 Lunalow+90%—$0.01Context: 2M → 1.05M
BetterClaude Haiku 5.5low×2.7—$0.024Context: 2M → 1M+6
BetterLing 3.0 FlashthinkingOpen+82%—$0.028Context: 2M → 262K+1ModelScoreCostPer taskWhat changes
Nothing here yet.
ModelScoreCostPer taskWhat changes
GPT-6 Lunalow+95%—$0.005Context: 2M → 1.05M+4GPT-5.6 Lunalow+90%—$0.01Context: 2M → 1.05MClaude Haiku 5.5low×2.7—$0.024Context: 2M → 1M+6Ling 3.0 FlashthinkingOpen+82%—$0.028Context: 2M → 262K+1MiMo v2.5thinkingOpen+97%—$0.042Context: 2M → 1MModelScoreCostPer taskWhat changes
MiMo v2.6 ProthinkingOpen×4.2—$0.13Context: 2M → 1M+4
DeepSeek V4.1 Flash 1017maxOpen×4.1—$0.26Context: 2M → 1M+5
GLM 5.3maxOpen×4—$2.01Context: 2M → 1M+5
Step 5 PreviewthinkingOpen×4—$1.03Context: 2M → 1M+3
Kimi K3maxOpen×3.9—$2.00Context: 2M → 1M+4ModelScoreCostPer taskWhat changes
Grok 4.6medium×3.9—$1.14Context: 2M → 500KGrok 4.7low×3.8—$1.03Context: 2M → 500K+5Grok 4.5high×3.5—$0.76Context: 2M → 500KGrok Build 0.1thinking×2.5—$1 / $2Context: 2M → 256KGrok 4.3medium×2.2—$1.25 / $2.50Context: 2M → 1MGrok 4.20 Multi-Agentn/a—$1.25 / $2.50Grok 4.20 Non-Reasoningn/a—$1.25 / $2.50Context: not verifiedGrok 4.20 Reasoningn/a—$1.25 / $2.50Context: not verifiedAll xAI models →History
2 versionsBenchmarks
all categoriesChat & Knowledge
Arena Text · overall1,419
Arena Text · Chinese1,457.1
Arena Text · English1,413.7
Arena Text · Korean1,331.5
Arena Text · non-English1,395.6
Arena Text · Polish1,428.2
Arena Text · Russian1,382.7
Arena Text · Spanish1,414.7
AA Omniscience Index-54.4
Vals LegalBench78.4
Vals MedScribe79.7
GPQA Diamond60.6
Coding
Agents & Tool Use
τ²-bench · AA63.7
Writing & Language
Vision & Documents
FAQ
How much does Grok 4 Fast cost?›
There is no per-unit API price: not available via API.
Is Grok 4 Fast free to use?›
There is no free API.
What is the context window of Grok 4 Fast?›
2M tokens.
When was Grok 4 Fast released? Is there a newer version?›
Released 2025-09-19. It has been superseded by Grok 4.3.
Is Grok 4 Fast open source?›
No, Grok 4 Fast is a closed model available through an API. The closest open-weights option here is MiMo v2.6 Pro.
Can Grok 4 Fast read images?›
It accepts text and images, PDF files as input.
What is Grok 4 Fast?›
Grok 4 Fast is a closed language model from xAI, released Sep 2025.
What are the best alternatives to Grok 4 Fast?›
GPT-6 Luna (better), MiMo v2.6 Pro (open weights).