Model decision surface
Compare AI models
Start with Claude Fable 5.1 and K2 Horizon 375B A23B, 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 K2 Horizon 375B A23B
Live dataset updated 9/13/2026, 2:40:29 PM UTC
Open 1200×630 evidence receipt| Field | Claude Fable 5.1 Anthropic | |
|---|---|---|
| ModelCap position | #1 | #30 |
| Index score | 87.1 | 67.3 |
| Evidence | Measured5 public benchmark observations across 5 boards | Estimatedglobal-corpus-prior over 186 held-out anchors (21%); launch card against 6 resolved peers on 11 rows (79%); optimism haircut 0 from cross-lab-probe; shrunk 4.1 toward the measured corpus |
| Input / 1M | $10.00 | Unavailable |
| Output / 1M | $50.00 | Unavailable |
| Pricing status | fresh | unavailable |
| Context | 1M | — |
| Providers | 4 | 0 |
| Weight access | API only | Open weights |
Decision facts
- Claude Fable 5.1 is #1; K2 Horizon 375B A23B is #30 on the same current language board.
- Index scores are 87.1 for Claude Fable 5.1 and 67.3 for K2 Horizon 375B A23B. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.
- Evidence differs: Claude Fable 5.1 is Measured; K2 Horizon 375B A23B is Estimated.
- Weight access differs: Claude Fable 5.1 is none; K2 Horizon 375B A23B is open.
- ModelCap currently lists 4 providers for Claude Fable 5.1 and 0 for K2 Horizon 375B A23B.
These are separate published fields, not a synthetic winner. ModelCap does not collapse price, access, context, and capability evidence into a hidden recommendation score.
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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.