# Grok 4.20 Beta Reasoning

Beta preview of SpaceXAI's Grok 4.20 extended thinking mode. Grok 4.20 Beta Reasoning generates chain-of-thought reasoning before answering, trading latency for deeper analysis on complex math, code, and multi-step problems.

- **Model ID:** `spacexai/grok-4.20-reasoning-beta`
- **Type:** chat
- **Providers:** xai
- **Context window:** 2,000,000
- **Maximum output tokens:** 2,000,000
- **Pricing:** $1.25/1M input tokens, $2.5/1M output tokens
- **Canonical page:** https://vercel.com/ai-gateway/models/grok-4.20-reasoning-beta

## Supported parameters

Detailed capability metadata has not been reported for this model.

## Example

```ts
import { streamText } from 'ai'

const result = streamText({
  model: 'spacexai/grok-4.20-reasoning-beta',
  prompt: 'Why is the sky blue?'
})
```

## About

Grok 4.20 Beta Reasoning was released March 11, 2026 as the beta-tagged variant of SpaceXAI's Grok 4.20 reasoning model. It generates visible chain-of-thought reasoning before producing its final answer, letting it work through multi-step problems, mathematical proofs, and complex code analysis more reliably than direct-response models.

The reasoning architecture adds latency per request but improves accuracy on tasks that benefit from deliberation: debugging intricate code paths, synthesizing information across long documents, and solving problems that require intermediate steps. Combined with the Grok 4.20 generation's low hallucination rates, this makes Grok 4.20 Beta Reasoning suitable for high-stakes analysis where correctness matters more than speed.

As a beta release, Grok 4.20 Beta Reasoning may receive weight or behavior updates. For stable reasoning workloads, use the non-beta `grok-4.20-reasoning`.

## What to consider

Grok 4.20 Beta Reasoning is in beta. Expect potential changes before general availability.

Extended thinking adds tokens and latency to each response. For tasks that don't benefit from structured reasoning, the non-reasoning variant is faster and cheaper.

## When to use

### Best For

- **Complex problem solving** requiring multi-step reasoning and extended thinking
- **Mathematical and scientific analysis** where structured chain-of-thought improves accuracy
- **Code debugging and review** that benefits from step-by-step logical analysis
- **High-stakes decisions** where low hallucination rates and traceable reasoning are critical
- **Research and analysis tasks** operating over large document collections within the context of 2M tokens

### Consider Alternatives When

- **Speed-focused tasks** where the Grok 4.20 Non-Reasoning variant delivers faster responses at lower cost
- **Multi-agent orchestration** where the Grok 4.20 Multi-Agent variant is purpose-built for agent collaboration
- **Stable production deployments** where beta models introduce risk. Use Grok 4.1 Fast Reasoning or the full Grok 4 instead
- **Simple direct-response tasks** where reasoning overhead adds cost without improving quality

## Best for

- **Complex problem solving** requiring multi-step reasoning and extended thinking
- **Mathematical and scientific analysis:** structured chain-of-thought improves accuracy
- **Code debugging and review** that benefits from step-by-step logical analysis
- **High-stakes decisions:** low hallucination rates and traceable reasoning are critical
- **Research and analysis tasks** operating over large document collections within the context of 2M tokens

## Consider alternatives

- **Speed-focused tasks:** the Grok 4.20 Non-Reasoning variant delivers faster responses at lower cost
- **Multi-agent orchestration:** the Grok 4.20 Multi-Agent variant is purpose-built for agent collaboration
- **Stable production deployments:** beta models introduce risk. Use Grok 4.1 Fast Reasoning or the full Grok 4 instead
- **Simple direct-response tasks:** reasoning overhead adds cost without improving quality

## Frequently asked questions

### What does 'reasoning' mean for Grok 4.20 Beta Reasoning?

Grok 4.20 Beta Reasoning generates chain-of-thought reasoning traces before producing final answers. This extended thinking improves accuracy on complex tasks at the cost of additional latency and tokens.

### What is the context window for Grok 4.20 Beta Reasoning?

2M tokens.

### Is Grok 4.20 Beta Reasoning in beta?

Yes. Grok 4.20 Beta Reasoning is currently in beta. Behavior, pricing, or availability may change before general availability.

### What does Grok 4.20 Beta Reasoning cost?

Rates are listed on this page. They reflect the providers routing through AI Gateway and shift when providers update their pricing.

### How do I authenticate with Grok 4.20 Beta Reasoning through Vercel AI Gateway?

Use your Vercel AI Gateway API key with `spacexai/grok-4.20-reasoning-beta` as the model identifier. AI Gateway manages routing and authentication automatically.

### Can I see the reasoning traces?

Yes. Chain-of-thought traces are included in the API response. You can inspect and log them for debugging and auditing.

### Does Vercel AI Gateway support Zero Data Retention for Grok 4.20 Beta Reasoning?

Yes, Zero Data Retention is available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.

## Links

- [Model page](https://vercel.com/ai-gateway/models/grok-4.20-reasoning-beta)
- [AI Gateway documentation](https://vercel.com/docs/ai-gateway)
- [Provider model documentation](https://docs.x.ai/developers/models/grok-4.20-beta-0309-reasoning)
- [Provider pricing](https://docs.x.ai/developers/models)