Model decision surface
Compare AI models
Start with Claude Fable 5.1 and Claude Sonnet 5.5, or choose any two current ranked language models. Compare capability evidence, price, context, provider availability, and weight access without pretending one field decides every use case.
Current public data
Claude Fable 5.1 vs Claude Sonnet 5.5
Live dataset updated 9/29/2026, 1:04:25 AM UTC
Open 1200×630 evidence receipt| Field | Claude Fable 5.1 Anthropic | Claude Sonnet 5.5 Anthropic |
|---|---|---|
| ModelCap position | #3 | #1 |
| Index score | 86.5 | 90.8 |
| Evidence | Measured5 public benchmark observations across 5 boards | Measured1 public benchmark observation across 1 board |
| Input / 1M | $10.00 | $2.00 |
| Output / 1M | $50.00 | $10.00 |
| Pricing status | fresh | fresh |
| Context | 1M | 1M |
| Providers | 4 | 5 |
| Weight access | API only | API only |
Decision facts
- Claude Fable 5.1 is #3; Claude Sonnet 5.5 is #1 on the same current language board.
- Index scores are 86.5 for Claude Fable 5.1 and 90.8 for Claude Sonnet 5.5. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.
- Both positions use Measured evidence.
- Listed output price per 1M tokens is $50.00 for Claude Fable 5.1 and $10.00 for Claude Sonnet 5.5. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $45.00 for Claude Fable 5.1 versus $9.00 for Claude Sonnet 5.5. Claude Sonnet 5.5 costs 80.0% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.
- Published context is 1,000,000 tokens for Claude Fable 5.1 and 1,000,000 for Claude Sonnet 5.5.
- ModelCap currently lists 4 providers for Claude Fable 5.1 and 5 for Claude Sonnet 5.5.
These are separate published fields, not a synthetic winner. ModelCap does not collapse price, access, context, and capability evidence into a hidden recommendation score.
Popular comparisons
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Each comparison page is a permanent, shareable URL with the same live figures as this tool: ModelCap Index position, API pricing, context window, provider count, weight access and every shared benchmark board.