o3 vs Grok 4 Fast
OpenAI o3 | SpaceXAI Grok 4 Fast | |
|---|---|---|
| Overview | ||
| Company | OpenAI | SpaceXAI |
| Release date | Apr 16 2025 | Sep 2025 |
| Access | Proprietary | Proprietary |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given 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. | 26% | — |
| Timeline | ||
| Release gap | o3 shipped 138 days before Grok 4 Fast | |
Which is better: o3 or Grok 4 Fast?
o3 and Grok 4 Fast don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. o3 shipped 138 days before Grok 4 Fast, 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 — o3 and Grok 4 Fast don't publish scores on any of the same benchmarks.
Frequently asked questions
o3 was released by OpenAI on Apr 16 2025.
Grok 4 Fast was released by SpaceXAI on Sep 2025.
Other comparisons
o3 vs Claude Sonnet 5Grok 4 Fast vs Claude Sonnet 5o3 vs Gemini OmniGrok 4 Fast vs Gemini Omnio3 vs Muse Spark 1.1Grok 4 Fast vs Muse Spark 1.1o3 vs DeepSeek-V4-ProGrok 4 Fast vs DeepSeek-V4-Proo3 vs Mistral Medium 3.5Grok 4 Fast vs Mistral Medium 3.5o3 vs Kimi K2.7 CodeGrok 4 Fast vs Kimi K2.7 Code