Claude Opus 4.5 vs GPT-5.5 Instant
Claude Opus 4.5 is cheaper on output tokens, while GPT-5.5 Instant offers a larger context window. Choose Claude Opus 4.5 or GPT-5.5 Instant based on the trade-off between cost, context, and the benchmarks that matter for your use case.
| Spec | Claude Opus 4.5 | GPT-5.5 Instant |
|---|---|---|
| Provider | Anthropic | ZenMux |
| Input / 1M tokens | $5.00 | $5.00 |
| Output / 1M tokens | $25.00 | $30.00 |
| Context window | 200K | 400K |
| Parameters | — | — |
| Open weights | No | No |
| Released | Nov 2025 | May 2026 |
| LiveBench score | 76.0 | — |
| SWE-bench Verified score | 79.2 | — |
| SWE-bench Multilingual score | 70.7 | — |
| LMArena (Chatbot Arena) Elo score | 1451 | 1419 |
| LMArena WebDev Elo score | 1493 | — |
| GPQA Diamond score | 86.0 | 82.5 |
| FrontierMath score | 20.7 | — |
| Epoch Capabilities Index score | 150 | 142 |
| LMArena Vision Elo score | — | 1250 |
FAQ
Is Claude Opus 4.5 or GPT-5.5 Instant cheaper?
Claude Opus 4.5 is cheaper on output tokens ($25.00 vs $30.00 per 1M).
Which has the larger context window, Claude Opus 4.5 or GPT-5.5 Instant?
GPT-5.5 Instant has the larger context window (400K tokens).
Pricing is indicative — confirm with the provider before production use. Highlighted values indicate the better figure for that row.