Grok 4.20 BetavsGLM-5.1
Grok 4.20 Beta | GLM-5.1 | |
|---|---|---|
| Specifications | ||
ParametersA rough measure of how big the model is. More parameters usually means more capable and more expensive to run, though it is a poor guide on its own — a smaller, newer model often beats a larger, older one. | — | 744B |
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | — | 200k |
| API pricingUSD per 1M tokens · lower wins · base tier | ||
Input priceWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it. | $1.25 | $1.40 |
Output priceWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one. | $2.50 | $4.40 |
Cached input priceA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again. | $0.20 | $0.26 |
| Benchmarks | ||
BullshitBench v2Nonsense detection — Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 56% | 22% |
Arena Elo (Text)Community preference — Real people chat with two anonymous AIs side by side and vote for the answer they prefer. Votes become a chess-style Elo rating on arena.ai — it measures which AI people actually like, not test scores. Higher is better. | 1475 | 1468 |
| BenchmarksPublished by one model only | ||
Next.js EvalsNext.js coding — Vercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | — | 75% |
Terminal-Bench 2.0Agentic terminal coding — Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? (Version 2.0 of the test.) Higher is better. | — | 63.5% |
BrowseCompWeb browsing — Can the AI browse the web and track down hard-to-find answers? Higher is better. | — | 68% |
Humanity's Last Exam · with toolsMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better. | — | 52.3% |
ARC-AGI-2Abstract reasoning — Puzzle-style tests of abstract reasoning and pattern-finding — the kind of thing people find easy but AIs often struggle with. Higher is better. | 53.3% | — |
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 86.2% |
Arena Elo (Code)Community preference (code) — Like the text arena, but people vote on which AI writes better code. The votes become a chess-style Elo rating on arena.ai. Higher is better. | — | 1510 |
| Overview | ||
| Company | SpaceXAI | Z.ai |
| Release date | Feb 17 2026 | Apr 7 2026 |
| Access | Proprietary | Open Weight |
Frequently asked questions
Grok 4.20 Beta leads GLM-5.1 on 2 of the 2 benchmarks they both report (BullshitBench v2, Arena Elo (Text)). Grok 4.20 Beta is cheaper on both input and output: $1.25 vs $1.40 per million input tokens, and $2.50 vs $4.40 per million output tokens. Figures are base-tier rates. Grok 4.20 Beta shipped 49 days before GLM-5.1, so benchmark comparisons should account for the intervening progress.
Grok 4.20 Beta is proprietary, while GLM-5.1 is open weight.
On BullshitBench v2, Grok 4.20 Beta leads at 56% vs GLM-5.1 at 22%. On Arena Elo (Text), Grok 4.20 Beta leads at 1475 vs GLM-5.1 at 1468.
Grok 4.20 Beta was released by SpaceXAI on Feb 17 2026.
GLM-5.1 was released by Z.ai on Apr 7 2026.
Grok 4.20 Beta is cheaper on both input and output: $1.25 vs $1.40 per million input tokens, and $2.50 vs $4.40 per million output tokens. Figures are base-tier rates. Rates are pay-as-you-go API prices verified on August 18, 2026.
Grok 4.20 Beta is a proprietary model released by SpaceXAI. GLM-5.1 is an open weight model released by Z.ai.