Anthropic released Claude Sonnet 4.6 on February 17, 2026. The headline: it performs within 1-2 points of Opus 4.6 on key benchmarks — at a fraction of the price. Early testers preferred it over Sonnet 4.5 about 70% of the time.
Key changes
| Sonnet 4.5 | Sonnet 4.6 | |
|---|---|---|
| Release date | Late 2025 | February 17, 2026 |
| Context window | 200K tokens | 1M tokens |
| SWE-bench Verified | 77.2% | 79.6% |
| OSWorld (computer use) | 61.4% | 72.5% |
| Adaptive thinking | No | Yes |
| Preferred over 4.5 | — | 70% of the time |
| Preferred over Opus 4.5 | — | 59% of the time |
| Input price | $3 / 1M tokens | $3 / 1M tokens |
| Output price | $15 / 1M tokens | $15 / 1M tokens |
What improved
Context window: 200K → 1M tokens. Same jump as Opus 4.6 — you can now process massive codebases and documents at Sonnet pricing.
Coding (SWE-bench): 77.2% → 79.6%. A meaningful improvement. Testers noted better context reading before modifying code and reduced logic duplication.
Computer use (OSWorld): 61.4% → 72.5%. A huge 18% jump in autonomous computer use — relevant if you’re building agents that interact with UIs.
Adaptive thinking. Like Opus 4.6, Sonnet 4.6 dynamically adjusts reasoning depth based on task complexity.
It beats Opus 4.5. Users preferred Sonnet 4.6 over the previous flagship Opus 4.5 in 59% of head-to-head comparisons. That’s remarkable for a model at one-fifth the price.
What stayed the same
- Pricing ($3/$15 per million tokens)
- API compatibility
Should you upgrade?
Yes. Same price, better at everything, bigger context window. Sonnet 4.6 is now the default model on claude.ai — Anthropic clearly considers it the go-to choice for most users.
FAQ
Is Sonnet 4.6 worth upgrading from 4.5?
Yes, without question. Same price ($3/$15 per million tokens), bigger context (1M vs 200K), better coding (79.6% vs 77.2% SWE-bench), massive computer use improvement (72.5% vs 61.4% OSWorld), and adaptive thinking. It even beats the previous Opus 4.5 in 59% of comparisons.
What changed from Sonnet 4.5 to 4.6?
The context window jumped from 200K to 1M tokens. SWE-bench coding improved from 77.2% to 79.6%. Computer use (OSWorld) jumped 18% from 61.4% to 72.5%. Adaptive thinking was added, which dynamically adjusts reasoning depth based on task complexity. Pricing stayed the same.
Is Sonnet 4.6 free?
Sonnet 4.6 is available on the free tier of claude.ai with usage limits. For heavier use, Claude Pro costs $20/month. Via the API, it costs $3/1M input tokens and $15/1M output tokens. There’s no permanently free unlimited access, but the free tier is generous enough for light use.
See our full AI Model Comparison for all models side by side.
Related: How to Choose an AI Coding Agent