This model is 16 months old. A newer version of it has since shipped: Claude Fable 5.1 (2026-09-01). The details below are still accurate for this model — it just is not what we would recommend today.
Claude Sonnet 4
Anthropic🇺🇸 United States
Launched alongside Claude Opus 4 as the balanced Claude 4 model. Hybrid instant/extended-thinking responses; later gained a 1M-token context beta. Superseded by Sonnet 4.5.
Context window200K tokens
Input / 1M tokens$3
Output / 1M tokens$15
Version History
claude-sonnet-4-launchmajor
Claude Sonnet 4 launches. Launched alongside Claude Opus 4 as the balanced Claude 4 model. Hybrid instant/extended-thinking responses; later gained a 1M-token context beta. Superseded by Sonnet 4.5.
Benchmark Scores
Full leaderboard →10.3%
Hallucination (Summarization)