Claude Sonnet 5.5 vs GPT-5.1-Codex
Both have similar output pricing, while Claude Sonnet 5.5 offers a larger context window. Choose Claude Sonnet 5.5 or GPT-5.1-Codex 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-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M tokens | $2.00 | $1.25 |
| Output / 1M tokens | $10.00 | $10.00 |
| Context window | 1M | 400K |
| Parameters | — | — |
| Open weights | — | No |
| Released | — | Nov 2025 |
| GPQA Diamond score | 95.6 | — |
| Epoch Capabilities Index score | 164 | — |
| LMArena (Chatbot Arena) Elo score | 1471 | — |
| LMArena WebDev Elo score | 1774 | 1337 |
| LMArena Vision Elo score | 1289 | — |
| LiveBench score | — | 69.3 |
| SWE-bench Verified score | — | 66.0 |
FAQ
Is Claude Sonnet 5.5 or GPT-5.1-Codex cheaper?
Claude Sonnet 5.5 and GPT-5.1-Codex have comparable output pricing.
Which has the larger context window, Claude Sonnet 5.5 or GPT-5.1-Codex?
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.