xAI: Grok 4.20 (Reasoning)
Grok 4.20 (Reasoning) is a reasoning model from xAI released on Mar 9, 2026. It reads text, images and files and writes text, with a 1M token context window and up to 30K tokens per reply.
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It costs $1.25 per million input tokens and $2.50 per million output tokens. Cached input bills at $0.20, 84% less than fresh input.
It supports tool calling, structured JSON output and prompt caching.
10 providers serve it, including OCI Generative AI, Vertex and DevPass (LLM Gateway).
- Modalities
- In / out price
- $1.25 / $2.50 per 1M
- Context
- 1M
- Max output
- 30K
- Released
- Mar 9, 2026
- Knowledge cutoff
- n/a
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Grok 4.20 (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 | $1.25 / 1M tokens | |
|---|---|---|
| Output | $2.50 / 1M tokens | |
| Cached input (read) | $0.20 / 1M tokens | 84% off input |
| Prompts over 200K | $2.50 in, $5 out | long context rate |
| Prompts over 200K | $2.50 in, $5 out | long context rate |
Grok 4.20 (Reasoning) providers
10 providers serve it, including OCI Generative AI, Vertex and DevPass (LLM Gateway). 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 |
|---|---|---|---|---|---|
| xAI First party | $1.25 | $2.50 | $0.20 | 1M | 30K |
| OCI Generative AI | $1.25 | $2.50 | $0.20 | 1M | 30K |
| Vertex | $1.25 | $2.50 | $0.20 | 2M | 30K |
| DevPass (LLM Gateway) | $1.25 | $2.50 | $0.20 | 2M | 30K |
| Eden AI | $1.25 | $2.50 | $0.20 | 1M | 30K |
| Impossibl | $1.25 | $2.50 | $0.20 | 1M | 30K |
| Merge Gateway | $1.25 | $2.50 | $0.20 | 1M | 1M |
| Tempr Gateway | $1.25 | $2.50 | $0.20 | 1M | 30K |
| Cloudflare AI Gateway | $2 | $6 | $0.20 | 2M | 30K |
| ZenMux | $2 | $6 | $0.20 | 2M | 30K |
What Grok 4.20 (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 4.20 (Reasoning) through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning - Temperature
temperature
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Grok 4.20 (Reasoning) questions
How much does the Grok 4.20 (Reasoning) API cost?
$1.25 per million input tokens and $2.50 per million output tokens, with cached input at $0.20. Prompts over 200K tokens bill at $2.50 input and $5 output. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Grok 4.20 (Reasoning)?
1,000,000 tokens of input, and it can write up to 30,000 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Grok 4.20 (Reasoning)?
10 providers serve it, including OCI Generative AI, Vertex and DevPass (LLM Gateway). Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Grok 4.20 (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 4.20 (Reasoning) open source?
No. xAI serves it through an API only, so you cannot download the weights or host it yourself.
When was Grok 4.20 (Reasoning) released?
Mar 9, 2026.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. Independent scores from my hand checked rankings, sources linked above. The summary is written from these facts.
Building on Grok 4.20 (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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