Grok 4.20
x-ai/grok-4.20-20260309
xAI: Grok 4.20, provided by x‑ai, accepts text, image, and file inputs and produces text output. It supports tools and reasoning, offers a context length of 2 000 000 tokens, and is priced at $1.25 per million input tokens and $2.5 per million output tokens. The model was released on 2026‑03‑31 and its weights are not open.
- tool use
- structured outputs
- reasoning
At a glance
Specifications
What the API gives you
- Context window
- 2M tokens
- Max output
- 1.8M tokens
- Input price
- $1.25 / 1M tokens
- Output price
- $2.50 / 1M tokens
- Cache read
- $0.20 / 1M tokens
- Modalities
- text, image, file → text
- Knowledge cutoff
- Sep 1, 2025
- Released
- Mar 9, 2026
Measured evidence
Public benchmark record
- Design Arena Coding
- 1207 Elo2026-10-20
- Design Arena Full-stack Agent
- 1054 Elo2026-10-14
- Design Arena UI
- 1190 Elo2026-10-20
- Design Arena Web-app Agent
- 1143 Elo2026-10-20
- Design Arena Website
- 1221 Elo2026-10-20
- LMArena WebDev
- 1376 Elo2026-10-19
LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. Design Arena uses blind human preference.
Task evidence
How broad is the support?
Each status is exact to this model version and the selected task. Official release claims remain provisional.
- Best LLM for Frontend & UIEstablished evidence
82% of intended weighted task evidence across 2 independent sources. 6 of 6 configured evaluation feeds currently have results.
- Best LLM for CodingEstablished evidence
36% of intended weighted task evidence across 2 independent sources. 7 of 7 configured evaluation feeds currently have results.
- Best LLM for Code CompletionProvisional evidence
36% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 3 of 3 configured evaluation feeds currently have results.
- Best Local LLM for CodingProvisional evidence
21% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 4 of 4 configured evaluation feeds currently have results.
- Best LLM for Agentic CodingProvisional evidence
20% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from LiveBench Agentic Coding or LMArena Agent. 7 of 7 configured evaluation feeds currently have results.
- Best LLM for Debugging & Code ReviewProvisional evidence
17% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 5 of 5 configured evaluation feeds currently have results.
Recommendation coverage
Where this model appears
Not currently included in a published recommendation. The task evidence panel above says exactly what is confirmed and what is still missing.
Catalog data via OpenRouter and models.dev. Last checked within the past 6 hours.