Claude Sonnet 4.6 vs GPT-5.5
Compare Claude Sonnet 4.6 and GPT-5.5 on the metrics that decide an agent workload.
| Metric | Claude Sonnet 4.6 | GPT-5.5 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M | $3.00 | $5.00 |
| Output / 1M | $15.00 | $30.00 |
| Cache read / 1M | $0.30 (−90%) | $0.50 (−90%) |
| Reuse-adj @55% | $4.89 | $9.39 |
| Context | 1M | 1.1M |
| Cache capture | 91% | 88% |
| Warm TTFT | 190ms (−65%) | 240ms (−67%) |
| Quality index | 90 | 96 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick Claude Sonnet 4.6 when it is cheaper once prefix reuse is priced in, it answers faster on warm cache hits, it captures more of the available reuse.
Pick GPT-5.5 when it scores higher on the composite quality index, it carries the larger 1.1M context window.
GPT-5.5 leads on quality while Claude Sonnet 4.6 leads on reuse-adjusted cost. Send latency- and budget-sensitive volume to Claude Sonnet 4.6 and reserve GPT-5.5 for the hard requests. Zumik's aliases route between them automatically under policy.
Claude Sonnet 4.6 vs GPT-5.5, answered.
Is Claude Sonnet 4.6 or GPT-5.5 cheaper?
At 55% prefix reuse, Claude Sonnet 4.6 blends to about $4.89 per 1M tokens and GPT-5.5 to about $9.39. Claude Sonnet 4.6 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 Sonnet 4.6 shows higher measured cache capture (91% 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.