xAI: Grok 4.1 Fast Reasoning
Grok 4.1 Fast Reasoning is a reasoning model from xAI released on Jun 27, 2025. It reads text, images and files and writes text, with a 1M token context window and up to 1M tokens per reply.
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It costs $0.20 per million input tokens and $0.50 per million output tokens. Cached input bills at $0.05, 75% less than fresh input.
It supports tool calling, structured JSON output and prompt caching.
9 providers serve it, including Azure, Vercel AI Gateway and Jiekou.AI. The lowest input price is $0.18 per million tokens at Jiekou.AI.
- Modalities
- In / out price
- $0.20 / $0.50 per 1M
- Context
- 1M
- Max output
- 1M
- Released
- Jun 27, 2025
- Knowledge cutoff
- n/a
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Grok 4.1 Fast Reasoning pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $0.20 / 1M tokens | |
|---|---|---|
| Output | $0.50 / 1M tokens | |
| Cached input (read) | $0.05 / 1M tokens | 75% off input |
Grok 4.1 Fast Reasoning providers
9 providers serve it, including Azure, Vercel AI Gateway and Jiekou.AI. The lowest input price is $0.18 per million tokens at Jiekou.AI. Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| Azure | $0.20 | $0.50 | $0.05 | 128K | 8K |
| Vercel AI Gateway | $0.20 | $0.50 | $0.05 | 1M | 1M |
| Jiekou.AI | $0.18 | $0.45 | – | 2M | 2M |
| 302.AI | $0.20 | $0.50 | – | 2M | 30K |
| DevPass (LLM Gateway) | $0.20 | $0.50 | $0.05 | 2M | 30K |
| FrogBot | $0.20 | $0.50 | $0.05 | 2M | 128K |
| Helicone | $0.20 | $0.50 | $0.05 | 2M | 2M |
| Poe | n/a | n/a | – | 2M | 30K |
| Qiniu | n/a | n/a | – | 20M | 2M |
What Grok 4.1 Fast Reasoning costs per month
Pick a workload close to yours or type your own volumes.
Supported request parameters
What you can set when you call Grok 4.1 Fast Reasoning through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning - Temperature
temperature
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Grok 4.1 Fast Reasoning questions
How much does the Grok 4.1 Fast Reasoning API cost?
$0.20 per million input tokens and $0.50 per million output tokens, with cached input at $0.05. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Grok 4.1 Fast Reasoning?
1,000,000 tokens of input, and it can write up to 1,000,000 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Grok 4.1 Fast Reasoning?
9 providers serve it, including Azure, Vercel AI Gateway and Jiekou.AI. The lowest input price is $0.18 per million tokens at Jiekou.AI. Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Grok 4.1 Fast Reasoning support tool calling?
Yes. It accepts tool definitions and can return JSON that matches a schema, which is what an agent needs to call your APIs.
Is Grok 4.1 Fast Reasoning open source?
No. xAI serves it through an API only, so you cannot download the weights or host it yourself.
When was Grok 4.1 Fast Reasoning released?
Jun 27, 2025.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. The summary is written from these facts.
Building on Grok 4.1 Fast Reasoning?
I test your real tasks on it and the two closest alternatives, then ship the agent on whichever wins on cost and accuracy.
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