Compare AI models
| Specifications | ||
Context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider. | 128k | 2M |
| Overview | ||
| Company | OpenAI | SpaceXSI |
| Release date | Feb 27 2025 | Sep 19 2025 |
| Access | Closed | Closed |
| Model details | View model | View model |
Other comparisons
GPT-4.5vsClaude Haiku 5.5Grok 4 FastvsClaude Haiku 5.5GPT-4.5vsGemini 4 ArgonGrok 4 FastvsGemini 4 ArgonGPT-4.5vsMuse Spark OpenGrok 4 FastvsMuse Spark OpenGPT-4.5vsDeepSeek-V4.1-Flash-1017Grok 4 FastvsDeepSeek-V4.1-Flash-1017GPT-4.5vsMistral Large 4Grok 4 FastvsMistral Large 4GPT-4.5vsKimi K3Grok 4 FastvsKimi K3Frequently asked questions
GPT-4.5 and Grok 4 Fast don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. GPT-4.5 shipped 204 days before Grok 4 Fast, so benchmark comparisons should account for the intervening progress.
Context windows are 128k (GPT-4.5) vs 2M (Grok 4 Fast).
Direct benchmark comparisons are unavailable — GPT-4.5 and Grok 4 Fast don't publish scores on any of the same benchmarks.