Claude Sonnet 5.5 vs GPT 5.5
Claude Sonnet 5.5 is from Anthropic, released September 28, 2026. GPT 5.5 is from OpenAI, released April 23, 2026.
- LMArena Elo1477 vs 1477. Both rated 1477 on LMArena.
- Input per 1M$2 vs $5. Claude Sonnet 5.5 costs 60% less per million input tokens.
- Output per 1M$10 vs $30. Claude Sonnet 5.5 costs 67% less per million output tokens.
- Context window1M vs 1.05M. GPT 5.5 takes 5.0% more context in one request.
Prices are the vendors’ published API rates; Elo is LMArena’s text board. Each figure is dated on its model page.
Interactive Comparison
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$2 / $10 per million tokens | $5 / $30 per million tokens | |
|---|---|---|
| Identity | ||
| Developer | Anthropic | OpenAI |
| Released | Sep 2026 | Apr 2026 |
| Status | GA | — |
| Licence | Proprietary | Proprietary |
| Self-hostable | No | No |
| Cost | ||
| Blended $/1M tokensinput × 0.75 + output × 0.25 | $4.000 / 1M tokens | $11.250 / 1M tokens |
| Input price | $2.000 / 1M tokens | $5.000 / 1M tokens |
| Output price | $10.000 / 1M tokens | $30.000 / 1M tokens |
| Cached input | $0.20 per 1M tokens | — |
| Batch discount | 50% ($1 / $5 per 1M tokens) | — |
| Capacity | ||
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128k tokens (up to 300k on the Message Batches API with the output-300k-2026-03-24 beta header) | 128K tokens |
| Capability | ||
| Vision in | Yes | — |
| Audio in | No | — |
| Function calling | Yes | — |
| Structured output | Yes | — |
| Extended reasoning | Yes - adaptive thinking, default effort high | — |
| Web search | Yes | — |
| Code execution | Yes | — |
| Access | ||
| API | Yes | — |
| Chat app | Yes | — |
| Cloud marketplaces | Amazon Bedrock, Google Cloud, Microsoft Foundry | — |
| Fine-tuning | No | — |
| Measured quality | ||
| LMArena Elo | 1477 (checked Oct 2026) | 1477 (checked Oct 2026) |
| LMArena rank | Rank 30 | Rank 31 |
| GPQA Diamond | 96 · max effort | 91 · low effort |
| Elo per dollarLMArena Elo ÷ blended $/1M tokens | 369 | 131 |
