Grok 4 Fast pricing
Grok 4 Fast API cost from xAI (Grok) — $0.200 per 1M input tokens and $0.500 per 1M output tokens. 2M context. Estimate your real monthly bill below, then compare it against every other model.
Fast / cheap 2M context · all prices USD per 1M tokens, list price last verified 2026-06-27.
Grok 4 Fast capabilities & limits
Representative specs for this tier — confirm exact limits in the xAI (Grok) docs.
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Call Grok 4 Fast from your code
The exact model string and endpoint to use. Works with the OpenAI SDK — just point base_url at the URL below.
grok-4-fasthttps://api.x.ai/v1XAI_API_KEYcurl https://api.x.ai/v1/chat/completions \
-H "Authorization: Bearer $XAI_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "grok-4-fast",
"messages": [{"role": "user", "content": "Hello"}]
}'Model strings follow each provider's naming convention; confirm the current id in the xAI (Grok) docs before relying on it.
What a Grok 4 Fast API call actually costs
Blended input + output cost at Grok 4 Fast's list rates — useful yardsticks before you commit to volume.
Grok 4 Fast cost calculator
Enter your monthly volume to estimate the Grok 4 Fast bill. Runs entirely in your browser.
xAI (Grok) models — Grok 4 Fast in context
How Grok 4 Fast prices against its siblings. Cheapest reference cost first.
| Model | Input /1M | Output /1M | Cost / call* | Context | Type |
|---|---|---|---|---|---|
| Grok 3 mini | $0.100 | $0.300 | $0.0004 | 128K | Fast / cheap |
| Grok 4 Fast 2M context | $0.200 | $0.500 | $0.0007 | 2M | Fast / cheap |
| Grok Code Fast 1 Code-specialised | $0.200 | $1.50 | $0.0017 | 256K | Balanced |
| Grok 4 Flagship | $3.00 | $15.00 | $0.018 | 256K | Flagship |
*Reference cost of one call with 1,000 input + 1,000 output tokens — a neutral yardstick. Use the calculator for your real usage. Cheapest row highlighted.
How Grok 4 Fast pricing works
Grok 4 Fast is billed per token: a lower input price of $0.200 per million tokens for everything you send, and a higher output price of $0.500 per million for everything the model generates. To turn that into a real Grok 4 Fast bill, multiply by your monthly request volume and average prompt/response length — the calculator above does exactly that.
Grok 4 Fast does not list a separate cached-input rate, so every input token bills at $0.200 per million. If repeated context is a big part of your prompts, a model with prompt caching may end up cheaper in practice.
List prices move fast — always confirm the current numbers on the official xAI (Grok) pricing page before relying on them for budgeting.
Grok 4 Fast pricing FAQ
How much does the Grok 4 Fast API cost?
Grok 4 Fast costs $0.200 per 1M input tokens and $0.500 per 1M output tokens. A typical 3K-input / 500-output call works out to about $0.0009.
What is Grok 4 Fast's context window?
Grok 4 Fast has a 2M-token context window. Tokens you put in the prompt are billed at the $0.200 per 1M input rate.
Does Grok 4 Fast charge extra for output tokens?
Yes. Output (generated) tokens cost $0.500 per 1M, versus $0.200 per 1M for input — about 2.5× more, which is normal for LLM APIs.
Is there a cheaper alternative to Grok 4 Fast?
In the same fast / cheap tier, Gemini 1.5 Flash-8B (Google) is cheaper at $0.037 in / $0.150 out. The overall cheapest model on the market is Gemini 1.5 Flash-8B.