1M-token context for Claude Sonnet 4 (beta)
Claude Sonnet 4 gets a 1M-token context window in beta on the API, five times its previous 200K limit.
Opens a 1M-token window to API users through a beta header. Rate limits were raised and Vertex AI support added on 2025-08-26. The 1M beta for Sonnet 4/4.5 was retired on 2026-04-30; 1M context went generally available at standard pricing for Opus 4.6 and Sonnet 4.6 on 2026-03-13.
- Date
- Tuesday, 12 August 2025
- Lab
- Anthropic
- Kind
- feature
- Access
- closed API
Figures
| Measure | Value | Measured by |
|---|---|---|
| Context window | 1M tokens beta, Claude Sonnet 4; previously 200K | company |
Claude 3 had offered 1M-token inputs to select customers since 2024-03-04 (claude-3-family). Source is the API release-notes page.
Sources
This record was checked against its sources on 6 October 2026. How we check