OpenAI's most powerful reasoning model — top across math, coding, and science.
Anthropic's Mythos-class flagship for ambitious, long-running professional work.
No shared demos for these models yet.
No captured outputs for these models yet.
Based on the Capability Index, Claude Fable 5 scores higher (91.6 vs 79.2). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.
o3 has a lower blended cost. o3: $2.00 input / $8.00 output. Claude Fable 5: $10.00 input / $50.00 output.
Claude Fable 5 has a larger context window: o3 supports 200K tokens vs Claude Fable 5 at 1M tokens.
Yes, both o3 and Claude Fable 5 support vision/image input.
Key differences: Claude Fable 5 has a notably higher capability index (12.4 point gap); o3 is significantly cheaper. 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 o3 and Claude Fable 5 for free on idapt.app to see which performs better for your specific needs.