GPT-5.6 Luna vs Grok 4.1 Fast
OpenAI GPT-5.6 Luna | xAI Grok 4.1 Fast | |
|---|---|---|
| Overview | ||
| Company | OpenAI | xAI |
| Release date | Jun 26 2026 | Nov 19 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. | — | 19% |
| Timeline | ||
| Release gap | Grok 4.1 Fast shipped 219 days before GPT-5.6 Luna | |
Which is better: GPT-5.6 Luna or Grok 4.1 Fast?
GPT-5.6 Luna and Grok 4.1 Fast don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Grok 4.1 Fast shipped 219 days before GPT-5.6 Luna, 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 — GPT-5.6 Luna and Grok 4.1 Fast don't publish scores on any of the same benchmarks.
Frequently asked questions
GPT-5.6 Luna was released by OpenAI on Jun 26 2026.
Grok 4.1 Fast was released by xAI on Nov 19 2025.
Other comparisons
GPT-5.6 Luna vs Claude Fable 5Grok 4.1 Fast vs Claude Fable 5GPT-5.6 Luna vs Gemini OmniGrok 4.1 Fast vs Gemini OmniGPT-5.6 Luna vs Muse SparkGrok 4.1 Fast vs Muse SparkGPT-5.6 Luna vs DeepSeek-V4-ProGrok 4.1 Fast vs DeepSeek-V4-ProGPT-5.6 Luna vs Mistral Medium 3.5Grok 4.1 Fast vs Mistral Medium 3.5GPT-5.6 Luna vs Kimi K2.7 CodeGrok 4.1 Fast vs Kimi K2.7 Code