Grok 4 FastvsGrok 4.20 Beta
Grok 4 Fast | Grok 4.20 Beta | |
|---|---|---|
| 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 |
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 |
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 |
| BenchmarksPublished by one model only | ||
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% |
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | — | 76.7% |
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% |
| Overview | ||
| Company | SpaceXAI | SpaceXAI |
| Release date | Sep 19 2025 | Feb 17 2026 |
| Access | Proprietary | Proprietary |
Other comparisons
Grok 4 FastvsClaude Fable 5.1Grok 4.20 BetavsClaude Fable 5.1Grok 4 FastvsGPT-6 AstraGrok 4.20 BetavsGPT-6 AstraGrok 4 FastvsGemini 3.8 FlashGrok 4.20 BetavsGemini 3.8 FlashGrok 4 FastvsMuse Spark 1.3Grok 4.20 BetavsMuse Spark 1.3Grok 4 FastvsDeepSeek-V4.1-FlashGrok 4.20 BetavsDeepSeek-V4.1-FlashGrok 4 FastvsMistral Medium 3.5Grok 4.20 BetavsMistral Medium 3.5
Frequently asked questions
Grok 4 Fast and Grok 4.20 Beta don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Only Grok 4.20 Beta has a verified first-party API price: $1.25 per million input tokens and $2.50 per million output tokens. No pay-as-you-go API rate is tracked for Grok 4 Fast. Grok 4 Fast shipped 151 days before Grok 4.20 Beta, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
Direct benchmark comparisons are unavailable — Grok 4 Fast and Grok 4.20 Beta don't publish scores on any of the same benchmarks.