Claude Opus 4.8 vs GPT-5.5 Pro
Top-tier reasoning for planning and hard debugging.
| Metric | Claude Opus 4.8 | GPT-5.5 Pro |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M | $5.00 | $30.00 |
| Output / 1M | $25.00 | $180.00 |
| Cache read / 1M | $0.50 (−90%) | $30.00 (−0%) |
| Reuse-adj @55% | $8.14 | $67.50 |
| Context | 1M | 1.1M |
| Cache capture | 93% | 90% |
| Warm TTFT | 240ms (−68%) | 900ms (−53%) |
| Quality index | 97 | 97 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
You want the highest composite quality and explicit caching control on long reasoning prefixes.
You prefer automatic caching and OpenAI tooling for deep-reasoning runs.
Both are reasoning.best candidates. Opus 4.8 edges quality; GPT-5.5 Pro is simpler to cache. Reserve either for genuinely hard work - token cost is high.
Claude Opus 4.8 vs GPT-5.5 Pro, answered.
Is Claude Opus 4.8 or GPT-5.5 Pro cheaper?
At 55% prefix reuse, Claude Opus 4.8 blends to about $8.14 per 1M tokens and GPT-5.5 Pro to about $67.50. Claude Opus 4.8 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 Opus 4.8 shows higher measured cache capture (93% vs 90%) 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.