Grok 4.20 0309 (Reasoning)
Grok 4.20 0309 (Reasoning) is an API model from xAI. It’s positioned for general text tasks—work that benefits from iteration, not just one-shot answers.
Intelligence
Good
Speed
Medium
110 tok/s output
Cost
High
$2.00 in / $6.00 out
Context
2M
Up to 2,000,000 tokens
How are Intelligence, Speed & Cost bucketed?
Intelligence and Speed buckets are percentile ranks on
Artificial Analysis. Cost buckets are fixed dollar
thresholds keyed off output-token price ($/M out).
Intelligence
- Top 1%≤ 1%
- Top 5%≤ 5%
- Top 10%≤ 10%
- Good≤ 25%
- Medium≤ 50%
- Below avg> 50%
Speed
- Top 1%≥ 345 tok/s
- Top 5%≥ 237 tok/s
- Top 10%≥ 196 tok/s
- Good≥ 146 tok/s
- Medium≥ 90 tok/s
- Slow< 90 tok/s
Cost
- Freeopen weights · self-host
- Low< $1 / M out
- Moderate$1–5 / M out
- High≥ $5 / M out
Core Capabilities
Long Documents
Handles entire codebases, books, and multi-doc RAG.
Context Window
2M tokens
≈ entire codebase
4k Chat 聊天
32k Long docs 长文档
128k Books 整本书
400k Multi-doc 多文档
1M Codebase 整个代码库
10M
2M
Availability
API
Available
Product / App
Not available
Open Source
Not released
Enterprise
Contact sales
Pricing Model
Pay per token
Input and output billed separately.
Pay-per-token Capability / Performance
Where this model sits relative to the middle 60% of models in the tree. All scores are 0–10 (higher is better).
Lower 20% Upper 80% This model
Context / memory
Context window size · log-scaled
6.0
9.0
10.0
Lower 20% 20th percentile — 20% of models score below this This model Where the current model lands Upper 80% 80th percentile — only 20% of models score above this
Percentile boundaries are computed across every model in the tree that reports the underlying benchmark for each capability.
What it feels like
- AA Intelligence Index of 73 at release — leading frontier slot, ahead of o3 (70), Gemini 2.5 Pro (70), Claude 4 Opus (64)
- GPQA Diamond all-time high of 88%; Humanity's Last Exam 24%; AIME 2024 94%; MMLU-Pro 87%
- Leads Coding Index (LiveCodeBench + SciCode) and Math Index (AIME24 + MATH-500)
Best use cases
- Math, science, and reasoning research where Grok 4 leads on raw benchmark numbers
- Real-time information lookup inside the X (Twitter) product with full timeline access
- Tool-using agents that benefit from extended reasoning + verifiable-rewards training
Tools to try
Not ideal for
- Customer-facing products where political-bias risk is a brand concern
- Workflows requiring system-prompt-free behaviour — RL tuning shows different defaults depending on scaffold
Model Evolution
grok is xAI's language model family.