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Claude Opus vs Sonnet
Claude Opus 5.5 costs exactly twice as much as Claude Sonnet 5.5 for every kind of token. Both have the same context and output limits. The differences are speed, default settings and what Anthropic built each one for.
Checked October 13, 2026 against Anthropic’s models overview and pricing page
| Claude Opus 5.5 | Claude Sonnet 5.5 | |
|---|---|---|
| What Anthropic says it is for | Long-running agentic coding and knowledge work | The best combination of speed and intelligence |
| Input, per 1M tokens | $4.00 | $2.00 |
| Cached input | $0.20 | $0.10 |
| Output | $20.00 | $10.00 |
| Batch input / output | $2.00 / $10.00 | $1.00 / $5.00 |
| Speed (Anthropic’s comparison) | Moderate | Fast |
| Thinking | Adaptive, always on | Adaptive |
| Default effort | Medium | High |
| Context window | 1M tokens | 1M tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Reliable knowledge cutoff | June 2026 | June 2026 |
| Fast mode | $8 in, $40 out (research preview) | Not offered |
| Retirement | Not sooner than 22 Sep 2027 | Not sooner than 28 Sep 2027 |
What Anthropic recommends
Anthropic’s models overview says to start with Claude Opus 5.5 for most workloads, if you are unsure which model to use. It describes Sonnet 5.5 as the best combination of speed and intelligence, and Claude Haiku 5.5 as the choice for high-volume, latency-sensitive tasks. Claude Fable 5.1 is for demanding reasoning and long agent tasks, or when Opus 5.5 at higher effort still falls short.
Price is easy to compare: Opus 5.5 is twice the cost of Sonnet 5.5 for input, cached input, output and batch. Quality is not. Which model gives good enough answers depends on your task, so run the same examples through both before you commit. This page compares prices and published specs only.
What the difference costs in a month
Change the numbers below to match your own use. Haiku 5.5 and Fable 5.1 are there to compare too.
Opus vs Sonnet for your use
Models
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Opus vs Sonnet in earlier generations
| Pair | Opus | Sonnet | Opus costs |
|---|---|---|---|
| Opus 5.5 / Sonnet 5.5 | $4.00 / $20.00 | $2.00 / $10.00 | 2× as much |
| Opus 5 / Sonnet 5 | $5.00 / $25.00 | $2.00 / $10.00 | 2.5× as much |
| Opus 4.6 / Sonnet 4.6 | $5.00 / $25.00 | $3.00 / $15.00 | 1.7× as much |
The price gap has moved between generations, from 1.7 times on the 4.6 models to 2.5 times on the 5 models and 2 times now. Opus 5.5 is the cheapest Opus Anthropic lists, at $4.00 in and $20.00 out.