Claude Sonnet 5.5 vs GPT-5.1-Instant
GPT-5.1-Instant is cheaper on output tokens, while Claude Sonnet 5.5 offers a larger context window. Choose Claude Sonnet 5.5 or GPT-5.1-Instant based on the trade-off between cost, context, and the benchmarks that matter for your use case.
| Spec | Claude Sonnet 5.5 | GPT-5.1-Instant |
|---|---|---|
| Provider | Anthropic | Poe |
| Input / 1M tokens | $2.00 | $1.10 |
| Output / 1M tokens | $10.00 | $9.00 |
| Context window | 1M | 128K |
| Parameters | — | — |
| Open weights | — | No |
| Released | — | Nov 2025 |
| LMArena (Chatbot Arena) Elo score | 1473 | — |
| GPQA Diamond score | 95.6 | — |
| LMArena WebDev Elo score | 1770 | — |
| Epoch Capabilities Index score | 166 | — |
| LMArena Vision Elo score | 1287 | — |
FAQ
Is Claude Sonnet 5.5 or GPT-5.1-Instant cheaper?
GPT-5.1-Instant is cheaper on output tokens ($9.00 vs $10.00 per 1M).
Which has the larger context window, Claude Sonnet 5.5 or GPT-5.1-Instant?
Claude Sonnet 5.5 has the larger context window (1M tokens).
Pricing is indicative — confirm with the provider before production use. Highlighted values indicate the better figure for that row.