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 17, 2026. Default version: Grok 4 Fast
LLMBoard Score53.4Grok 4 Fast
Coverage80%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 | Score95.0% | Rank02 | Participants47 | Percentile97.8% | EvidenceC | Evaluated |
| BenchmarkLiveCodeBench | Score80.0% | Rank11 | Participants75 | Percentile86.5% | EvidenceC | Evaluated |
| BenchmarkHMMT 2025 | Score93.3% | Rank13 | Participants33 | Percentile62.5% | EvidenceC | Evaluated |
| BenchmarkAIME 2025 | Score92.0% | Rank39 | Participants115 | Percentile66.7% | EvidenceC | Evaluated |
| BenchmarkBrowseComp | Score44.9% | Rank51 | Participants62 | Percentile18.0% | EvidenceC | Evaluated |
| BenchmarkGPQA | Score85.7% | Rank54 | Participants239 | Percentile77.7% | EvidenceC | Evaluated |
| BenchmarkHumanity's Last Exam | Score20.0% | Rank64 | Participants99 | Percentile35.7% | EvidenceC | 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 | Rank20 | Rating / score1170.3 | Votes42,981 | ObservationsN/A | Result date |
| Arenasearch style control | Categoryoverall | Rank24 | Rating / score1159.6 | Votes42,981 | ObservationsN/A | Result date |
| Arenasearch factuality | Categoryoverall | Rank25 | Rating / score1147.0 | Votes30,241 | ObservationsN/A | Result date |
| Arenatext style control | Categoryoverall | Rank109 | Rating / score1420.1 | Votes6,834 | ObservationsN/A | Result date |
| Arenatext | Categoryoverall | Rank121 | Rating / score1408.5 | Votes6,834 | 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 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 | LLMBoard53.4 | 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 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 2026-08-17.
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, GLM 4.6, GPT-5.5-Instant.