AnthropicSightingClaude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) debuts at #2
Confirmed18 evidence links
Anthropic · model family
Claude Sonnet models
Claude Sonnet has 4 versions on record. The first released was Claude Sonnet 4.5 on 29 Sep 2025, the latest Claude Sonnet 5.5 on 28 Sep 2026.
Every released version 4
USD / 1M tokens
| Model | Context window | Input USD / 1M tokens | Output USD / 1M tokens | Status |
|---|---|---|---|---|
Claude Sonnet 5.5Anthropic | 1M | $2.00 | $10.00 | Released · |
Claude Sonnet 5Anthropic | 1M | $2.00 | $10.00 | Released · |
Claude Sonnet 4.6Anthropic | 1M | $3.00 | $15.00 | Released · |
Claude Sonnet 4.5Anthropic | 200K | $3.00 | $15.00 | Released · |
Latest signals
AnthropicSighting