Grok 4.20 Beta (Reasoning, 0309)
Made by xAI. Epoch AI does not state how it can be accessed. No Top tier or Strong results yet among the models listed here.
In short
What it does well
No Top tier or Strong ratings on the four main tests yet.
Where it falls short
- Coding: Behind the leaders (61st of 77 listed models)
- Writing: Middle (50th of 77 listed models)
What we don't know yet
- Hard maths problems: Not enough data
- School-competition maths: Not enough data
- Graduate-level science questions: Not enough data
- Short factual questions: Not enough data
- Fixing real software bugs: Not enough data
- Difficult coding tasks: Not enough data
The four ratings
- Top tier
- Strong
- Middle
- Behind the leaders
- Not enough data
Ratings compare only the 77 models listed here, in quarters, best first. “Not enough data” means no result yet. It is never a low score.
- Writing
- MiddleHow often people preferred its answers to writing prompts. 1,432 on Arena's scale · Source for Grok 4.20 Beta (Reasoning, 0309) writing score (lmarena)
- Coding
- Behind the leadersHow often people preferred its answers to coding questions. 1,459 on Arena's scale · Source for Grok 4.20 Beta (Reasoning, 0309) coding score (lmarena)
- Maths
- Not enough dataNo result yet for hard maths problems.
- Knowledge
- Not enough dataNo result yet for short factual questions.
Evidence completeness: Partial evidence, 7 of 13 tests have a result.
Where it is relatively stronger or weaker
This compares each kind of request with the model's own overall position among the 77 listed models, using Arena's votes. It is about performance on different languages, kinds of request and topics, not about political or social bias.
Relatively stronger
No category stands out as clearly stronger than its overall position.
Relatively weaker
- Expert-level prompts: 68th of 77 on prompts that need expert knowledge, against 43rd of 77 overall. Source for Expert-level prompts
- German: 45th of 55 on questions asked in German, against 43rd of 77 overall. Source for German
- Long prompts: 61st of 77 on long, detailed prompts, against 43rd of 77 overall. Source for Long prompts
Show every category we can see
| Category | Position | Arena score | Votes | Source |
|---|---|---|---|---|
| Expert-level prompts Kind of request | 68th of 77 | 1,439 95% range 1,431 to 1,447 | 6,694 | Source for Expert-level prompts |
| Hard prompts Kind of request | 59th of 77 | 1,452 95% range 1,447 to 1,456 | 43,501 | Source for Hard prompts |
| Long prompts Kind of request | 61st of 77 | 1,437 95% range 1,432 to 1,442 | 29,106 | Source for Long prompts |
| Longer conversations Kind of request | 43rd of 77 | 1,456 95% range 1,449 to 1,462 | 12,122 | Source for Longer conversations |
| Chinese Language | 58th of 76 | 1,481 95% range 1,471 to 1,491 | 4,234 | Source for Chinese |
| English prompts Language | 47th of 77 | 1,457 95% range 1,452 to 1,462 | 30,431 | Source for English prompts |
| French Language | 33rd of 72 | 1,476 95% range 1,462 to 1,490 | 2,216 | Source for French |
| German Language | 45th of 55 | 1,441 95% range 1,422 to 1,460 | 1,051 | Source for German |
| Japanese Language | 38th of 54 | 1,414 95% range 1,391 to 1,438 | 706 | Source for Japanese |
| Korean Language | 34th of 54 | 1,415 95% range 1,396 to 1,435 | 1,067 | Source for Korean |
| Non-English prompts Language | 42nd of 77 | 1,441 95% range 1,436 to 1,445 | 35,991 | Source for Non-English prompts |
| Russian Language | 38th of 77 | 1,458 95% range 1,450 to 1,465 | 7,432 | Source for Russian |
| Spanish Language | 51st of 70 | 1,443 95% range 1,429 to 1,457 | 2,062 | Source for Spanish |
| Entertainment, sport and media Topic | 46th of 77 | 1,426 95% range 1,420 to 1,432 | 14,778 | Source for Entertainment, sport and media |
| Law and government Topic | 48th of 76 | 1,454 95% range 1,445 to 1,463 | 5,327 | Source for Law and government |
| Medicine and health Topic | 48th of 75 | 1,454 95% range 1,445 to 1,463 | 4,952 | Source for Medicine and health |
| Science Topic | 45th of 77 | 1,463 95% range 1,456 to 1,469 | 10,867 | Source for Science |
| Software and IT Topic | 60th of 77 | 1,461 95% range 1,456 to 1,466 | 26,051 | Source for Software and IT |
Bias: what we can and can't see
Our sources do not measure political lean, stereotyping, flattery (agreeing with you too readily) or safety behaviour, so we cannot say how any model does on those. What we can show is above: where a model is relatively stronger or weaker across languages, kinds of request and topics. Also, people voting in Arena can favour answer style, such as length and formatting, and our numbers do not adjust for that. See what AI bias means and what these tests can tell you.
Best-supported use cases
- Homework and maths: not ranked, because there is not enough data for the main test.
- Research and checking facts: not ranked, because there is not enough data for the main test.
Where an alternative might be more suitable
- Writing and creating content: rated Middle on writing votes. Compare it with Claude Opus 5.5, the best-supported choice for this task.
- Coding and building things: rated Behind the leaders on coding votes. Compare it with Claude Opus 5.5, the best-supported choice for this task.
- Homework and maths: no result on hard maths problems, so we cannot say. See which models the evidence does support.
- Business emails and everyday work: rated Middle on business-task votes. Compare it with Gemini 4 Argon, the best-supported choice for this task.
- Research and checking facts: no result on short factual questions, so we cannot say. See which models the evidence does support.
What it is
- Maker
- xAI
- Access, as listed by Epoch AI
- Not stated
- Licence, as listed by Arena
- Proprietary
- Last observation in our data
- 28 Oct 2026
- Data last changed
- 29 Oct 2026, 14:36 UTC
We have not verified an official product page for this model, so we do not link to one.
How you can use it
Proprietary. The model's files are not published, so it is generally available only through its maker or partners the maker chooses.
How you can reach it (an app, a website, a developer API or a third-party tool) and what that costs are not covered by our benchmark data. Where we could verify prices from the maker's own pages, they are shown under Price. See models, apps and harnesses and how AI pricing works.
Price
Price not independently verified
See Grok (checked 29 Oct 2026). Page opened and read. It says Grok is 'free to try on the web and in the apps' and that SuperGrok adds higher limits. It states no prices or model names. The separate plans page opens as a sign-up pop-up showing introductory offers and no model names, so we record nothing else.
We never infer subscription prices from API prices. New to “tokens” and “per million”? See how AI pricing works.
Good to remember
- Benchmarks are samples of tasks. None proves performance in every situation.
- Arena scores come from people choosing between answers. That measures preference, not correctness.
- Ratings are relative to the 77 models listed here. A different set would change them.
- Sources test models at different settings. Each result shows the setting used, and we do not adjust it.
The evidence, for the curious
Show all 13 tests with settings and sources
| Test | Result | Rating | Setting used | Source identifier | Observed | Links |
|---|---|---|---|---|---|---|
| Arena text: overall preference Arena 'text' leaderboard (Bradley-Terry rating, no style control) |
1,451 Arena score 95% range 1,447 to 1,455, 66,422 votes |
Middle | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: overall preference score (lmarena) |
| Arena text: creative writing Arena 'text' leaderboard, category creative_writing |
1,432 Arena score 95% range 1,425 to 1,439, 11,423 votes |
Middle | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: creative writing score (lmarena) |
| Arena text: coding Arena 'text' leaderboard, category coding |
1,459 Arena score 95% range 1,453 to 1,464, 18,368 votes |
Behind the leaders | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: coding score (lmarena) |
| Arena text: maths Arena 'text' leaderboard, category math |
1,455 Arena score 95% range 1,445 to 1,466, 3,542 votes |
Middle | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: maths score (lmarena) |
| Arena text: following instructions Arena 'text' leaderboard, category instruction_following |
1,421 Arena score 95% range 1,415 to 1,426, 22,630 votes |
Behind the leaders | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: following instructions score (lmarena) |
| Arena text: business and management Arena 'text' leaderboard, category industry_business_and_management_and_financial_operations |
1,432 Arena score 95% range 1,426 to 1,438, 13,361 votes |
Middle | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · text/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena text: business and management score (lmarena) |
| Arena WebDev: building web apps Arena 'webdev' leaderboard (Code Arena), category overall |
1,375 Arena score 95% range 1,369 to 1,382, 15,404 votes |
Behind the leaders | effort: Reasoning, 0309, bradley-terry rating | Grok 4.20 Beta (Reasoning, 0309) lmarena · webdev/latest |
28 Oct 2026 | Source for Grok 4.20 Beta (Reasoning, 0309) Arena WebDev: building web apps score (lmarena) |
| FrontierMath Tiers 1-3 (v2) | Not enough data | |||||
| OTIS Mock AIME 2024-2025 | Not enough data | |||||
| GPQA Diamond | Not enough data | |||||
| SimpleQA Verified | Not enough data | |||||
| SWE-bench Verified (Epoch runs) | Not enough data | |||||
| FrontierCode (reported by Cognition) | Not enough data | |||||
Missing evidence
Not enough data for these tests:
- FrontierMath Tiers 1-3 (v2)
- OTIS Mock AIME 2024-2025
- GPQA Diamond
- SimpleQA Verified
- SWE-bench Verified (Epoch runs)
- FrontierCode (reported by Cognition)
Missing results are not low scores and do not count against the model.
Where a source gives no public run log, we cannot show the run behind the score. See data sources.
Not sure this is the right one?
Tell us what you need help with and we'll narrow the options down.