xAI · Released Nov 19, 2025Grok 4.1 Fast
xAI's fast agentic tool-calling model with a 2M context window; non-reasoning variant for low-latency responses.
- Capability
- —No ECI score yet
- Input
- $0.20per 1M tokens
- Output
- $0.50per 1M tokens
- Context
- 2M30K max output
What it costs
- Input
- $0.20per million tokens
- Output
- $0.50per million tokens
- Blended (3:1)
- $0.275cheaper than 73% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $0.65 |
| Team assistant25M input + 5M output tokens | $7.50 |
| Production app250M input + 50M output tokens | $75.00 |
Median of 2 paid API providers on models.dev.
Independent benchmarks
Epoch AI has not published a Capabilities Index score for Grok 4.1 Fast yet.
The details
- Lab
- xAI
- Released
- Nov 19, 2025
- Context window
- 2,000,000 tokens
- Max output
- 30,000 tokens
- Inputs
- Text, Images
- Output
- Text
- Reasoning
- No
- Tool calling
- Yes
- Structured output
- Yes
- Weights
- Proprietary
- Availability
- 2 API providerslisted on models.dev
More from xAI
About Grok 4.1 Fast
How much does Grok 4.1 Fast cost?
Grok 4.1 Fast costs $0.20 input / $0.50 output per million tokens (median across 2 API providers). At a 3:1 input-to-output mix that is $0.275 per million tokens, cheaper than 73% of the 360 priced models we track.
What is the context window of Grok 4.1 Fast?
Grok 4.1 Fast accepts up to 2,000,000 tokens per request and can write up to 30,000 tokens in one response.
How good is Grok 4.1 Fast?
Epoch AI has not published a Capabilities Index score for Grok 4.1 Fast yet.
Is Grok 4.1 Fast open source?
No. Grok 4.1 Fast is proprietary; you use it through an API or partner platforms.
What inputs does Grok 4.1 Fast support?
Grok 4.1 Fast accepts text and images and replies in text. It is not a dedicated reasoning model, supports tool calling and can return structured JSON output.
When was Grok 4.1 Fast released?
xAI released Grok 4.1 Fast on Nov 19, 2025.
What are the best alternatives to Grok 4.1 Fast?
The closest current models from other labs on capability, price and release date are Ministral 3 14B (Mistral AI, $0.268 / $0.325), GLM-4.6V-Flash (Z.ai (Zhipu), $0.161 / $0.559), Solar Pro 3 (Upstage, $0.25 / $0.25) and Jamba Mini (AI21 Labs, $0.20 / $0.40).