Anthropic introduces Claude Sonnet 5.5
Anthropic released Claude Sonnet 5.5, the second model in its Claude 5.5 family. It generates output over 30 percent faster, costs up to 30 percent less per task, and nearly matches Opus 5.5 on knowledge-work benchmarks, with Terminal-Bench rising from 10.3 to 70.6 percent.
How Claude Sonnet 5.5 compares
List prices per million tokens, context and Arena's text leaderboard, against Anthropic's other top models and the leading labs' best. The percentages are Claude Sonnet 5.5's price against each.
| Model | Released | Input | Output | Context | Arena |
|---|---|---|---|---|---|
| Claude Sonnet 5.5 | September 2026 | $2.00 | $10.00 | 1M | not ranked yet |
| Claude Sonnet 5 | June 2026 | $2.00 | $10.00 | 1M | #46 1462 |
| Claude Opus 5.5 | September 2026 | $4.00 -50% | $20.00 -50% | 1M | #1 1509 |
| GPT-6 Astra | September 2026 | $10.00 -80% | $50.00 -80% | 1.05M | #23 1478 |
| Gemini 3.1 Pro | $2.00 | $12.00 -17% | 2M | #14 1487 | |
| Qwen3.8 Max Prime | September 2026 | $4.00 -50% | $12.00 -17% | 1M | not ranked yet |
Arena ranks the best effort setting of each model among all models on its text leaderboard. Every model and price.
What the sources say
Linked, never rewritten. Official means the lab itself.
Press4
TechCrunch· 28 Sep, 18:00Anthropic releases Sonnet 5.5, which it calls a significantly cheaper, faster work partnerSiliconANGLE· 28 Sep, 18:00Anthropic debuts Claude Sonnet 5.5 running 30% faster than the previous-generation AI modelThe Decoder· 28 Sep, 18:02Anthropic's Claude Sonnet 5.5 nearly matches Opus 5.5 on benchmarks while costing up to 30 percent less per taskOpenRouter· 28 Sep, 18:04Anthropic: Claude Sonnet 5.5 listed on OpenRouterCommunity6
Hacker News· 28 Sep, 17:58Claude Sonnet 5.552 points · 13 commentsHacker News· 28 Sep, 18:00Claude Sonnet 5.516 points · 5 commentsr/singularity· 28 Sep, 18:02Claude Sonnet 5.5 Releasedr/ClaudeAI· 28 Sep, 18:02Sonnet 5.5 is out!!r/ClaudeAI· 28 Sep, 18:03Sonnet 5.5 available in Claude Appr/singularity· 28 Sep, 18:05Claude Sonnet 5.5 ReleasedHow it unfolded
Every source in the order it appeared. Times in UTC.
What the numbers did
Signals for Anthropic from two hours before this story to ten days after: leaderboards, app charts, usage, prices and status.