Claude Fable 5.1 vs Claude Sonnet 5
Claude Fable 5.1 vs Claude Sonnet 5: which AI model is cheaper, has the larger context window and more capabilities? Side-by-side comparison updated daily.
Quick verdict
- Claude Sonnet 5 is 5.0× cheaper than Claude Fable 5.1 for the same mix of input and output tokens.
- Both have the same context window.
- Claude Fable 5.1 is the more recent release (Sep 1, 2026).
- Claude Fable 5.1 scores higher on independent tests (overall index 165.0 vs 156.3).
- Choose Claude Sonnet 5 if cost matters most; choose Claude Fable 5.1 if you need its specific strengths above. For the best results, test both on your own prompts.
| Claude Fable 5.1 | Claude Sonnet 5 | |
|---|---|---|
| Company | Anthropic | Anthropic |
| Released | Sep 1, 2026 ● | Jun 30, 2026 |
| Overall index | 165.0 ● | 156.3 |
| GPQA Diamond | — | 90.5% |
| AIME math | 100% ● | 94.7% |
| FrontierMath | 90.2% ● | 65.6% |
| SimpleQA Verified | 70.8% ● | 33.7% |
| Input (per 1M tokens) | $10 | $2 ● |
| Output (per 1M tokens) | $50 | $10 ● |
| Cost for 1M input + 1M output tokens | $60.00 | $12.00 ● |
| Providers | 4 | 10 ● |
| Context | 1M | 1M |
| Max output | 128K | 128K |
| Inputs | Text, Image, Files | Text, Image, Files |
| Outputs | Text | Text |
| Reasoning | ✓ | ✓ |
| Tool use | ✓ | ✓ |
| Structured output | ✓ | ✓ |
| Open weights | — | — |