GPT-5.5 vs Claude Fable 5
The two default flagships for general and coding agents.
| Metric | GPT-5.5 | Claude Fable 5 |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Input / 1M | $5.00 | $10.00 |
| Output / 1M | $30.00 | $50.00 |
| Cache read / 1M | $0.50 (−90%) | $1.00 (−90%) |
| Reuse-adj @55% | $9.39 | $16.29 |
| Context | 1.1M | 1M |
| Cache capture | 88% | 93% |
| Warm TTFT | 240ms (−67%) | 280ms (−70%) |
| Quality index | 96 | 98 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
You want automatic caching with zero breakpoint management, a slightly cheaper input price, and native audio in the modality mix.
You can place explicit breakpoints on stable blocks and want the higher cache-read discount and the strongest measured capture on coding traffic.
For hands-off reuse, GPT-5.5. For squeezing maximum cache savings on a well-structured agent prompt, Claude Fable 5. Zumik routes auto.best to whichever wins under current policy.
GPT-5.5 vs Claude Fable 5, answered.
Is GPT-5.5 or Claude Fable 5 cheaper?
At 55% prefix reuse, GPT-5.5 blends to about $9.39 per 1M tokens and Claude Fable 5 to about $16.29. GPT-5.5 is cheaper on that basis.
Which has the larger context window?
GPT-5.5 has the larger window: 1.1M vs 1M tokens.
Which captures more reuse?
Claude Fable 5 shows higher measured cache capture (93% vs 88%) in the Zumik corpus.
Let an alias pick for you.
Route to whichever model wins under current policy automatically. Zumik resolves the alias to the best fit per request, so you never hard-code a loser.