xAI
Grok Build 0.1: price, context window, and caching
xAI's dedicated agentic coding model, which also answers to the older grok-code-fast ids.
Released May 2026 · Prices as of September 28, 2026
In xAI’s words
“xAI's coding model, trained specifically for agentic coding workflows.”
What xAI says it’s good at
- Agentic software engineering and workflow tasks, with function calling, structured outputs, and reasoning Source
Facts
Specs and prices
| Fact | Grok Build 0.1 |
|---|---|
| Maker | xAI |
| API model id | grok-build-0.1 |
| Released | May 2026 |
| Status | Preview |
| Context window | 256K tokens |
| Max output | Not published |
| Open weights | No |
| Input, per 1M tokens | $1 |
| Cache hit, per 1M | $0.20 |
| Cache write, per 1M | $1 (same as input) |
| Output, per 1M tokens | $2 |
| Runs in | OpenCode and OpenRouter |
Standard API rates in US dollars, as published by the maker on September 28, 2026. Batch and priority tiers, taxes, and subscription plans are not included. Grok Build 0.1: Once a prompt reaches 200K tokens, every token in the request costs $2 input, $0.40 cached, and $4 output per million.
Good to know
- xAI announced it as early access in May 2026.
- GitHub Copilot retired Grok Code Fast 1 on May 15, 2026.
Cost
What typical work costs
Example token counts at Grok Build 0.1’s published rates. On the agentic session, caching saves $1.60 against billing every token as ordinary input.
| Agentic coding session, 100K input, 400K written to cache, 2M read from cache, 50K output | $1.00 |
|---|---|
| Large one-off review, 150K input with no cache hits, 10K output | $0.17 |
| Output-heavy generation, 30K input, 80K output | $0.19 |
| A month of sessions, 110 sessions: 5 a day, 22 working days | $110.00 |
Prompt caching
How xAI bills cached tokens
xAI
The xAI API caches repeated prompt prefixes automatically. Sending the same conversation id with each request raises the hit rate.
xAI lists no fee for writing the cache. A cache hit costs $0.50 per million tokens on Grok 4.7 and $0.20 on Grok Build 0.1.
Source: xAI docs: Prompt caching
Grok Build 0.1 compared
Grok 4.7 vs Grok Build 0.1
Grok Build 0.1 costs $1.00 per cached coding session against $2.30 on Grok 4.7. Both follow xAI's caching and 200K rules; they differ on window and status.
Grok Build 0.1 vs Claude Sonnet 5
Grok Build 0.1 costs $1.00 per cached coding session against $2.40 on Claude Sonnet 5, but it is in early access, with a 256K window and a price step at 200K.
Grok Build 0.1 vs Gemini 3.8 Flash
Gemini 3.8 Flash costs $0.71 per cached coding session against $1.00 on Grok Build 0.1, until its introductory rates end on December 31, 2026.
Grok Build 0.1 vs GPT-6 Luna
GPT-6 Luna charges a tenth of Grok Build 0.1's input price, and a cached coding session costs $0.11 against $1.00. What each model is for, and where it runs.
Your own numbers
See what Grok Build 0.1 really costs you.
everyaitoken reads your OpenRouter history on your Mac and prices every request at API rates, with what caching saved or cost. $9 once.