Multi-Step Reasoning
Processes problems through deliberate, sequential reasoning steps before generating a response, improving accuracy on complex analytical and logical tasks.
X.ai
Grok 4.20 Reasoning
Grok 4.20 Reasoning is an experimental, reasoning-focused text generation model developed by xAI, the AI division of X. It is part of the Grok 4.20 beta series and is specifically designed to work through problems using deliberate, multi-step thinking before producing a response. This approach improves accuracy on tasks where a direct answer is likely to fall short, such as mathematical problem-solving, logical analysis, and scientific reasoning. The model supports a context window of 2,000,000 tokens, allowing it to process and reason over very long documents or extended conversation histories in a single pass. It is accessible through the xAI inference provider via the Inworld Router or Realtime API, making it straightforward to integrate into developer applications. Use cases where it is particularly well-suited include research assistance, code debugging, nuanced question answering, and any workflow that benefits from structured, step-by-step analysis.
March 2026
2,000,000 context
2,000,000 tokens output
Multi-Step Reasoning
Large Context Window
Mathematical Problem-Solving
Code Debugging
Scientific Reasoning
API Integration
Model Overview
High-signal model metadata in a structured two-column overview table.
Provider
The entity that provides this model.
X.ai
Input Context Window
The number of tokens supported by the input context window.
2,000,000
tokens
Maximum Output Tokens
The number of tokens that can be generated by the model in a single request.
2,000,000 tokens
tokens
Open Source
Whether the model's code is available for public use.
No
Release Date
When the model was first released.
March 2026
Knowledge Cut-off Date
When the model's knowledge was last updated.
March 2026
API Providers
The providers that offer this model. This is not an exhaustive list.
xAI API, OpenAI API
Modalities
Types of data this model can process.
Text
Code
What is Grok 4.20 Reasoning
A fuller summary of positioning, capabilities, and source-specific details for Grok 4.20 Reasoning.
Grok 4.20 Reasoning is an experimental, reasoning-focused text generation model developed by xAI, the AI division of X. It is part of the Grok 4.20 beta series and is specifically designed to work through problems using deliberate, multi-step thinking before producing a response. This approach improves accuracy on tasks where a direct answer is likely to fall short, such as mathematical problem-solving, logical analysis, and scientific reasoning.
The model supports a context window of 2,000,000 tokens, allowing it to process and reason over very long documents or extended conversation histories in a single pass. It is accessible through the xAI inference provider via the Inworld Router or Realtime API, making it straightforward to integrate into developer applications. Use cases where it is particularly well-suited include research assistance, code debugging, nuanced question answering, and any workflow that benefits from structured, step-by-step analysis.
Capabilities
What Grok 4.20 Reasoning supports
Large Context Window
Supports a context window of 2,000,000 tokens, enabling processing of very long documents or extended conversation histories in a single request.
Mathematical Problem-Solving
Applies structured reasoning to mathematical challenges, working through equations and proofs step by step rather than producing a direct answer.
Code Debugging
Analyzes code to identify errors and trace logic issues using multi-step reasoning, making it useful for diagnosing non-obvious bugs.
Scientific Reasoning
Handles research and science-oriented queries by reasoning through hypotheses, evidence, and conclusions in a structured manner.
API Integration
Accessible via the xAI inference provider through the Inworld Router or Realtime API, supporting integration into developer applications and A/B testing configurations.
Pricing for Grok 4.20 Reasoning
Primary API pricing shown in the same “quick compare” spirit as the reference page.
Input tokens
$2.00
Per million tokens
Output tokens
N/A
Per million tokens
Price Comparison
Additional usage-cost dimensions synced into the project for this model.
maxTemperature
1
maxResponseSize
2,000,000 tokens
API Access & Providers
Places where this model is available, based on the synced detail-page metadata.
xAI API
OpenAI API
Model Performance
Benchmark scores synced from the current model source and normalized into the local catalog.
| Benchmark | Score |
|---|---|
|
GPQA Diamond
PhD-level science questions (biology, physics, chemistry)
|
|
|
HLE
Questions that challenge frontier models across many domains
|
|
|
SciCode
Scientific research coding and numerical methods
|
Resources & Documentation
Official model cards, release notes, docs, and other references synced from the source page.
Community discussion
What people think about Grok 4.20 Reasoning
Grok 4.20 Reasoning discussions are most active in r/just4ochat, r/commonstack, r/grok. Top Reddit threads cluster around benchmark and model-comparison threads, coding workflow discussions.
The strongest match in this snapshot has 12 upvotes and 6 comments.
Hey all,
🚢 Quick ship today. Grok 4.20 Reasoning and Non-Reasoning are rolling out to users today on [www.just4o.chat](http://www.just4o.chat)
These models are a large step forward for xAI in their race to catch up to the frontier AI labs, but they admittedly still have a ways to go to be competitive with GPT 5.4 Pro or Claude Opus 4.6 Extended Thinking when it comes to coding, spreadsheet, or enterprise intelligence tasks.
That said, Grok continues to set records predicting real world events, conducting sentiment analysis using X, and even tops benchmarks on some portfolio management challenges we've seen.
Yesterday, we added gpt-5.4-mini + gpt-5.4-nano to the platform, so there's lots of new stuff to check out; stay tuned for 'echo-instant' coming soon, alongside GLM models with both a normal and a 'fast' setting!
(look into Cerebras online; and get ready for 1,000 - 3,000 token/second speeds!)
All the best,
just4o
xAI’s grok 4.20 is available on Commonstack!
leading with 2M context windows xAI brings awesome agentic models!
try both now:
xAI Grok 4.20 reasoning: https://commonstack.ai/model-library/model?modelId=f0251135-19aa-4bb2-981a-faa2f1b285dd
xAI Grok 4.20 non-reasoning: https://commonstack.ai/model-library/model?modelId=5c00acc6-ec5a-4f64-9cdf-3e71824d23a0
I tried and is not working... STATUS = 200 but ADD = 400 with "Model grok-4.20-reasoning not supported for endpoint xai\_api.Chat/GetCompletion."
FAQ
Common questions about Grok 4.20 Reasoning
What is the context window size for Grok 4.20 Reasoning?
Grok 4.20 Reasoning supports a context window of 2,000,000 tokens, which allows it to process very long documents or extended conversation histories within a single request.
What is the training data cutoff for this model?
According to the available metadata, the training date for Grok 4.20 Reasoning is listed as March 2026.
How is Grok 4.20 Reasoning different from a standard Grok 4.20 model?
Grok 4.20 Reasoning is an experimental variant specifically designed to work through problems using deliberate, multi-step reasoning before generating a response. This is intended to improve accuracy on complex tasks compared to a standard generation approach.
How can I access Grok 4.20 Reasoning?
The model is available through the xAI inference provider and can be accessed via the Inworld Router or Realtime API. It can also be used directly through MindStudio without requiring separate API key management.
What types of tasks is Grok 4.20 Reasoning best suited for?
Based on the model's design, it is best suited for tasks that benefit from structured, multi-step analysis — including mathematical problem-solving, code debugging, scientific reasoning, research assistance, and nuanced question answering.
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