# Grok 4.20 Reasoning

Grok 4.20 Reasoning supports extended thinking for complex problem-solving, combining chain-of-thought reasoning with the low hallucination rates of the Grok 4.20 generation.

- **Model ID:** `spacexai/grok-4.20-reasoning`
- **Type:** chat
- **Providers:** xai, vertex
- **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

## 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',
  prompt: 'Why is the sky blue?'
})
```

## About

Grok 4.20 Reasoning was released March 10, 2026 as the reasoning-enabled variant of SpaceXAI's Grok 4.20 beta generation. It supports extended thinking for complex problem-solving tasks, generating chain-of-thought reasoning traces before producing final answers. The model maintains the low hallucination rates and strict prompt adherence from the Grok 4.20 foundation.

The reasoning capability improves accuracy on tasks that benefit from structured thinking: mathematical problem solving, code debugging, logical analysis, and multi-step planning. Reasoning traces are visible in the API response, providing transparency you can use for debugging and auditing.

This model is currently in beta.

## What to consider

Grok 4.20 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 Reasoning?

Grok 4.20 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 Reasoning?

2M tokens.

### Is Grok 4.20 Reasoning in beta?

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

### What does Grok 4.20 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 Reasoning through Vercel AI Gateway?

Use your Vercel AI Gateway API key with `spacexai/grok-4.20-reasoning` 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 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)
- [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)