xAI model product
Grok 4 Fast
Grok 4 Fast is a high-speed variant of Grok-4 from xAI, optimized for faster inference with improved throughput and lower latency.
Updated Sep 8, 2026. Default version: Grok 4 Fast
LLMBoard Score52.3Grok 4 Fast
Coverage40%7 benchmark families
Context window2MTokens
Official input priceN/AOfficial price unavailable
Grok 4 Fast Capability Profile
This profile uses the model's current scored version. Arena ratings and prices are shown separately.
Grok 4 Fast Benchmark Results
Benchmark scores for Grok 4 Fast.
Sort by
Benchmark | Score | Rank | Participants | Percentile | Evidence | Evaluated |
|---|
| BenchmarkSimpleQA | Score95.00% | Rank02 | Participants47 | Percentile97.83% | EvidenceC | Evaluated |
| BenchmarkLiveCodeBench | Score80.00% | Rank11 | Participants75 | Percentile86.49% | EvidenceC | Evaluated |
| BenchmarkHMMT 2025 | Score93.30% | Rank13 | Participants33 | Percentile62.50% | EvidenceC | Evaluated |
| BenchmarkLM Arena Search | Score1,170.51 rating | Rank18 | Participants28 | Percentile37.04% | EvidenceA | Evaluated |
| BenchmarkLM Arena Search Factuality | Score1,146.67 rating | Rank23 | Participants28 | Percentile18.52% | EvidenceA | Evaluated |
| BenchmarkLM Arena Search Style Control | Score1,160.31 rating | Rank23 | Participants28 | Percentile18.52% | EvidenceA | Evaluated |
| BenchmarkAIME 2025 | Score92.00% | Rank40 | Participants119 | Percentile66.95% | EvidenceC | Evaluated |
| BenchmarkBrowseComp | Score44.90% | Rank52 | Participants63 | Percentile17.74% | EvidenceC | Evaluated |
| BenchmarkGPQA | Score85.70% | Rank58 | Participants247 | Percentile76.83% | EvidenceC | Evaluated |
| BenchmarkHumanity's Last Exam | Score20.00% | Rank68 | Participants103 | Percentile34.31% | EvidenceC | Evaluated |
| BenchmarkLM Arena Text Style Control | Score1,418.26 rating | Rank89 | Participants210 | Percentile57.89% | EvidenceA | Evaluated |
| BenchmarkLM Arena Text | Score1,406.57 rating | Rank97 | Participants210 | Percentile54.07% | EvidenceA | Evaluated |
Grok 4 Fast Arena Results
Preference and agent-evaluation results for the default version.
Sort by
Arena | Category | Rank | Rating / score | Votes | Observations | Result date |
|---|
| Arenasearch | Categoryoverall | Rank18 | Rating / score1,170.51 | Votes41,794 | ObservationsN/A | Result date |
| Arenasearch factuality | Categoryoverall | Rank23 | Rating / score1,146.67 | Votes29,409 | ObservationsN/A | Result date |
| Arenasearch style control | Categoryoverall | Rank23 | Rating / score1,160.31 | Votes41,794 | ObservationsN/A | Result date |
| Arenatext style control | Categorypolish | Rank52 | Rating / score1,443.63 | Votes376 | ObservationsN/A | Result date |
| Arenatext style control | Categoryindustry mathematical | Rank62 | Rating / score1,444.91 | Votes309 | ObservationsN/A | Result date |
| Arenatext | Categorypolish | Rank63 | Rating / score1,426.93 | Votes376 | ObservationsN/A | Result date |
| Arenatext | Categoryindustry mathematical | Rank68 | Rating / score1,435.34 | Votes309 | ObservationsN/A | Result date |
| Arenatext style control | Categoryspanish | Rank74 | Rating / score1,420.67 | Votes255 | ObservationsN/A | Result date |
| Arenatext style control | Categorymath | Rank79 | Rating / score1,424.51 | Votes382 | ObservationsN/A | Result date |
| Arenatext style control | Categorychinese | Rank80 | Rating / score1,463.60 | Votes461 | ObservationsN/A | Result date |
| Arenatext | Categorychinese | Rank82 | Rating / score1,456.52 | Votes461 | ObservationsN/A | Result date |
| Arenatext style control | Categoryindustry medicine and healthcare | Rank83 | Rating / score1,442.37 | Votes378 | ObservationsN/A | Result date |
| Arenatext | Categorycreative writing | Rank84 | Rating / score1,388.02 | Votes886 | ObservationsN/A | Result date |
| Arenatext | Categorylonger query | Rank84 | Rating / score1,413.62 | Votes1,411 | ObservationsN/A | Result date |
| Arenatext | Categorymath | Rank85 | Rating / score1,418.35 | Votes382 | ObservationsN/A | Result date |
| Arenatext | Categoryspanish | Rank86 | Rating / score1,415.09 | Votes255 | ObservationsN/A | Result date |
| Arenatext | Categoryindustry entertainment and sports and media | Rank87 | Rating / score1,380.43 | Votes1,202 | ObservationsN/A | Result date |
| Arenatext | Categoryindustry writing and literature and language | Rank87 | Rating / score1,390.32 | Votes1,456 | ObservationsN/A | Result date |
| Arenatext | Categorymulti turn | Rank88 | Rating / score1,413.74 | Votes1,084 | ObservationsN/A | Result date |
| Arenatext style control | Categoryindustry software and it services | Rank88 | Rating / score1,455.72 | Votes2,064 | ObservationsN/A | Result date |
| Arenatext style control | Categorymulti turn | Rank88 | Rating / score1,422.28 | Votes1,084 | ObservationsN/A | Result date |
| Arenatext style control | Categorynon english | Rank88 | Rating / score1,404.40 | Votes3,692 | ObservationsN/A | Result date |
| Arenatext style control | Categoryexclude ties | Rank89 | Rating / score1,407.43 | Votes4,543 | ObservationsN/A | Result date |
| Arenatext style control | Categoryoverall | Rank89 | Rating / score1,418.26 | Votes6,336 | ObservationsN/A | Result date |
| Arenatext | Categoryindustry software and it services | Rank90 | Rating / score1,431.27 | Votes2,064 | ObservationsN/A | Result date |
| Arenatext | Categorycoding | Rank91 | Rating / score1,429.79 | Votes1,180 | ObservationsN/A | Result date |
| Arenatext style control | Categorycreative writing | Rank91 | Rating / score1,384.05 | Votes886 | ObservationsN/A | Result date |
| Arenatext style control | Categoryenglish | Rank93 | Rating / score1,426.95 | Votes2,644 | ObservationsN/A | Result date |
| Arenatext style control | Categoryindustry entertainment and sports and media | Rank93 | Rating / score1,383.00 | Votes1,202 | ObservationsN/A | Result date |
| Arenatext style control | Categoryindustry writing and literature and language | Rank94 | Rating / score1,392.83 | Votes1,456 | ObservationsN/A | Result date |
Grok 4 Fast Pricing
Official vendor API pricing appears first, followed by individual provider offers.
- Official API
- N/A
- Official provider
- N/A
- Lowest third-party
- From $0.20 input, $0.50 output per 1M via ZenMux
- Tracked offerings
- 1
Sort by
Provider | Provider model ID | Region | Input / 1M | Output / 1M | Context | Updated |
|---|
| ProviderZenMux | Provider model IDx-ai/grok-4-fast | Regionglobal | Input / 1M$0.20 | Output / 1M$0.50 | Context2M | Updated |
Official prices use only the vendor's configured official Provider and positive standard USD PAYG rates. Third-party offers remain explicitly labeled.
Grok 4 Fast Runtime Performance
Provider-specific output speed and catalog latency for Grok 4 Fast. Runtime does not affect the capability score.
Sort by
Provider | Output Speed | Catalog Latency | Max Input | Max Output | Updated |
|---|
| ProviderxAI | Output Speed90.00 tok/s | Catalog LatencyN/A | Max Input2M | Max Output30K | Updated |
Output Speed is generated output tokens received per second. Catalog latency is reported separately from observed provider TTFT.
Grok 4 Fast Specifications
Technical details for the model's default version.
- Version
- Grok 4 Fast
- Released
- Aug 28, 2025
- Knowledge cutoff
- Unknown
- Parameters
- N/A
- Context window
- 2M
- Max output
- 30K
- Inputs
- image, text
- Outputs
- text
- Open weights
- No
- License
- Proprietary
Grok 4 Fast Versions
Available versions of this model. The score column identifies the version used in the overall ranking.
Sort by
Version | Released | LLMBoard | Parameters | Context | Max output | Open weights | License |
|---|
| VersionGrok 4 Fast | Released | LLMBoard52.32 | ParametersN/A | Context2M | Max output30K | Open weightsNo | LicenseProprietary |
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What is Grok 4 Fast?
Key information about Grok 4 Fast and its available data.
Grok 4 Fast is a large language model from xAI and a high-speed variant of Grok-4. It is optimized for faster inference while maintaining strong reasoning capabilities.
Data as of 2026-09-08.
FAQ
Common questions about Grok 4 Fast.
When was Grok 4 Fast released?
Grok 4 Fast's default version was released on Aug 28, 2025.
How much does Grok 4 Fast cost?
No official standard PAYG price is currently available for Grok 4 Fast. The lowest tracked third-party offer starts at $0.20 input and $0.50 output via ZenMux.
Who created Grok 4 Fast?
Grok 4 Fast was created by xAI.
What is the context window for Grok 4 Fast?
The default version has a 2M token context window.
Is Grok 4 Fast open weight?
No. The default version is not marked as having publicly available weights.
How many API providers offer Grok 4 Fast?
1 provider offerings are linked to the default version.