Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Opus 5.5 is from Anthropic, released September 22, 2026. Claude Sonnet 5.5 is from Anthropic, released September 28, 2026.
- LMArena Elo1509 vs 1477. Claude Opus 5.5 is 2.2% ahead on LMArena Elo.
- Input per 1M$4 vs $2. Claude Sonnet 5.5 costs 50% less per million input tokens.
- Output per 1M$20 vs $10. Claude Sonnet 5.5 costs 50% less per million output tokens.
- Context window1M vs 1M. Both hold 1M tokens of context.
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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$4 / $20 per million tokens | $2 / $10 per million tokens | |
|---|---|---|
| Identity | ||
| Developer | Anthropic | Anthropic |
| Released | Sep 2026 | Sep 2026 |
| Status | GA | GA |
| Licence | Proprietary | Proprietary |
| Self-hostable | No | No |
| Cost | ||
| Blended $/1M tokensinput × 0.75 + output × 0.25 | $8.000 / 1M tokens | $4.000 / 1M tokens |
| Input price | $4.000 / 1M tokens | $2.000 / 1M tokens |
| Output price | $20.000 / 1M tokens | $10.000 / 1M tokens |
| Cached input | $0.20 per 1M tokens | $0.20 per 1M tokens |
| Batch discount | 50% ($2 / $10 per 1M tokens) | 50% ($1 / $5 per 1M tokens) |
| Capacity | ||
| Context window | 1M tokens | 1M tokens |
| Max output | 128k tokens | 128k tokens (up to 300k on the Message Batches API with the output-300k-2026-03-24 beta header) |
| Capability | ||
| Vision in | Yes | Yes |
| Audio in | No | No |
| Function calling | Yes | Yes |
| Structured output | Yes | Yes |
| Extended reasoning | Yes | Yes - adaptive thinking, default effort high |
| Web search | Yes | Yes |
| Code execution | Yes | Yes |
| Access | ||
| API | Yes | Yes |
| Chat app | Yes | Yes |
| Cloud marketplaces | Amazon Bedrock, Google Cloud, Microsoft Foundry | Amazon Bedrock, Google Cloud, Microsoft Foundry |
| Fine-tuning | No | No |
| Measured quality | ||
| LMArena Elo | 1509 (checked Nov 2026) | 1477 (checked Nov 2026) |
| LMArena rank | Rank 3 | Rank 31 |
| GPQA Diamond | 91 · max effort | 96 · max effort |
| Elo per dollarLMArena Elo ÷ blended $/1M tokens | 189 | 369 |
