xAI's Opus-class flagship for frontier coding, agentic tool use, and knowledge work.
OpenAI's most powerful reasoning model — top across math, coding, and science.
No shared demos for these models yet.
No captured outputs for these models yet.
Based on the Capability Index, Grok 4.5 scores higher (88.5 vs 79.2). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.
Grok 4.5 has a lower blended cost. Grok 4.5: $2.00 input / $6.00 output. o3: $2.00 input / $8.00 output.
Grok 4.5 has a larger context window: Grok 4.5 supports 500K tokens vs o3 at 200K tokens.
Yes, both Grok 4.5 and o3 support vision/image input.
Key differences: Grok 4.5 has a notably higher capability index (9.3 point gap). Compare full specs on this page.
If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Grok 4.5 and o3 for free on idapt.app to see which performs better for your specific needs.