xAI model product
Grok 4 Fast
Grok 4 Fast is a high-speed variant of Grok-4, optimized for faster inference while maintaining strong reasoning capabilities.
Updated Aug 12, 2026. Default version: Grok 4 Fast
LLMBoard score54.0Grok 4 Fast
Coverage80%7 benchmark families
Context window2MTokens
Official input priceN/AOfficial price unavailable
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 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.
| SimpleQA | 95.0% | 02 | 46 | 97.8% | C | |
| LiveCodeBench | 80.0% | 09 | 73 | 88.9% | C | |
| HMMT 2025 | 93.3% | 13 | 33 | 62.5% | C | |
| AIME 2025 | 92.0% | 39 | 114 | 66.4% | C | |
| BrowseComp | 44.9% | 48 | 58 | 17.5% | C | |
| GPQA | 85.7% | 50 | 234 | 79.0% | C | |
| Humanity's Last Exam | 20.0% | 59 | 93 | 37.0% | C |
Grok 4 Fast Arena Results
Preference and agent-evaluation results for the default version.
| search | overall | 20 | 1170.3 | 42,981 | N/A | |
| search style control | overall | 24 | 1159.6 | 42,981 | N/A | |
| search factuality | overall | 25 | 1147.0 | 30,241 | N/A | |
| text style control | overall | 108 | 1420.1 | 6,836 | N/A | |
| text | overall | 120 | 1408.5 | 6,836 | N/A |
Grok 4 Fast Runtime Performance
Provider-specific output speed and catalog latency for Grok 4 Fast. Runtime does not affect the capability score.
| xAI | 10.206 tok/s | N/A | 2M | 30K |
Output Speed is generated output tokens received per second. Catalog latency is reported separately from observed provider TTFT.
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
| ZenMux | x-ai/grok-4-fast | global | $0.20 | $0.50 | 2M |
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 Versions
Available versions of this model. The score column identifies the version used in the overall ranking.
| Grok 4 Fast | 54.0 | N/A | 2M | 30K | No | Proprietary |
What is Grok 4 Fast?
Key information about Grok 4 Fast and its available data.
Grok 4 Fast is a high-speed variant of Grok-4, optimized for faster inference while maintaining strong reasoning capabilities. It offers improved throughput and lower latency compared to the standard Grok-4 model.
Data as of 2026-08-11.
Grok 4 Fast vs nearby models
Open a comparison with the three ranked models immediately above and below this model.
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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.
What models should I compare Grok 4 Fast with?
Nearby ranked alternatives include MAI Thinking 1, Grok 3, GLM 4.6.