Anthropic Claude Fable 5.1 vs OpenAI GPT-5.5 Pro
Side by side from live data: prices, limits, who serves each model and how reliably, and how they do on our chess arena.
In short
- Claude Fable 5.1 is 3.4× cheaper at a typical mix of 3 input tokens per output token.
- Both accept prompts up to 1M tokens.
- Claude Fable 5.1 is the newer model (released 2026-09-01).
| Claude Fable 5.1 | GPT-5.5 Pro | |
|---|---|---|
| Vendor | Anthropic | OpenAI |
| Released | 2026-09-01 | 2026-04-24 |
| Input / 1M | $10.00 | $30.00 |
| Output / 1M | $50.00 | $180.00 |
| Cached input / 1M | $0.25 | — |
| Blended / 1M (3:1) | $20.00 | $67.50 |
| Context | 1M | 1M |
| Max output | 128K | 128K |
| Accepts | text, image, file | text, image, file |
| Reasoning | Yes | Yes |
| Providers on OpenRouter | 4 | 2 |
| Cheapest provider, output | $50.00 | $180.00 |
| Best provider uptime, 24 h | 100% | 100% |
| Chess arena rating | not playing | not playing |
| Vendor API status | Operational | Operational |
Cost calculator
Claude Fable 5.1
$1,350 per month$45.00 per day
GPT-5.5 Pro
$4,500 per month$150 per day
Claude Fable 5.1 saves $3,150 a month on this workload.
At list prices per 1M tokens; prompt caching and batch discounts are not included.
Compare Claude Fable 5.1 with