Claude Fable 5 vs GPT-5.5 Pro
Compare Claude Fable 5 and GPT-5.5 Pro on the metrics that decide an agent workload.
| Metric | Claude Fable 5 | GPT-5.5 Pro |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M | $10.00 | $30.00 |
| Output / 1M | $50.00 | $180.00 |
| Cache read / 1M | $1.00 (−90%) | $30.00 (−0%) |
| Reuse-adj @55% | $16.29 | $67.50 |
| Context | 1M | 1.1M |
| Cache capture | 93% | 90% |
| Warm TTFT | 280ms (−70%) | 900ms (−53%) |
| Quality index | 98 | 97 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick Claude Fable 5 when it scores higher on the composite quality index, it is cheaper once prefix reuse is priced in, it answers faster on warm cache hits.
Pick GPT-5.5 Pro when it carries the larger 1.1M context window.
Claude Fable 5 wins on both reuse-adjusted cost and quality here, so it is the default pick. Reach for GPT-5.5 Pro only when a specific constraint (modality, latency floor, or licensing) forces it.
Claude Fable 5 vs GPT-5.5 Pro, answered.
Is Claude Fable 5 or GPT-5.5 Pro cheaper?
At 55% prefix reuse, Claude Fable 5 blends to about $16.29 per 1M tokens and GPT-5.5 Pro to about $67.50. Claude Fable 5 is cheaper on that basis.
Which has the larger context window?
GPT-5.5 Pro has the larger window: 1.1M vs 1M tokens.
Which captures more reuse?
Claude Fable 5 shows higher measured cache capture (93% vs 90%) in the Zumik corpus.
Let an alias pick for you.
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