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For well-scoped everyday tasks, Claude Sonnet 5.5 is the lower-cost choice; for complex, open-ended work that needs sustained judgment, Anthropic positions Opus 5.5 as the better fit. Sonnet’s listed API token rates are half Opus’s, but the available evidence does not establish that standard Sonnet 5.5 is faster than standard Opus 5.5 in a direct comparison.
What differs between Sonnet 5.5 and Opus 5.5?
Anthropic announced Opus 5.5 on September 22, 2026, then Sonnet 5.5 on September 28. The company describes Sonnet as a faster, lower-cost complement to Opus: Sonnet is aimed at well-scoped everyday tasks, while Opus is aimed at more complex work requiring careful judgment. That is Anthropic’s product positioning, not a guarantee that one model will outperform the other on your task.
The price and speed figures below are from Anthropic’s model pages, published in 2026. API rates are per million tokens and are not consumer subscription prices.
| Measure | Sonnet 5.5 | Opus 5.5 |
|---|---|---|
| Input API tokens | $2 per million | $4 per million |
| Output API tokens | $10 per million | $20 per million |
| Cache-read tokens | $0.20 per million | $0.20 per million |
| Cache-write tokens | $2.50 per million | $5 per million |
| Published speed statement | Anthropic says output is 30%+ faster than Sonnet 5 | Fast mode is listed as up to 2.5× faster, with separate, higher rates |
| Anthropic’s suggested work | Everyday tasks, bug fixing, polished documents, slides, and spreadsheets | Complex coding and documents, computer use, and sustained judgment |
Sources: Anthropic’s Sonnet 5.5 page and Anthropic’s Opus 5.5 page.
Is Sonnet 5.5 faster than Opus 5.5?
There is no direct, controlled standard-mode latency comparison in the cited Anthropic material that establishes Sonnet 5.5 is faster than Opus 5.5. The “30%+ faster” statement compares Sonnet 5.5 with its predecessor, Sonnet 5. Opus’s “up to 2.5× faster” claim refers to its separate Fast mode, which has higher API rates; it is not a standard Sonnet-versus-Opus result.
Actual response time can also depend on the product, workload, effort setting, and configuration. Anthropic says lower effort settings answer faster and use fewer tokens, while higher settings spend longer reasoning and checking work. Its apps and Claude Code default to Medium effort, while Claude Platform defaults to High, so comparisons across those environments may not be like-for-like. For latency-sensitive work, compare both models using the same prompts, product, settings, and representative workload.
Which model is cheaper for API use?
At the listed 2026 API rates, Sonnet costs half as much per million input tokens and half as much per million output tokens. Cache reads are listed at the same rate for both; cache writes cost less with Sonnet. Your task’s total bill depends on how many input, output, and cached tokens it uses, plus whether you use Opus Fast mode. The rates are published by Anthropic and may change.
These figures apply to API usage, not to Claude consumer subscriptions. Anthropic lists Sonnet 5.5 in Claude on web, iOS, and Android, and for developers through Claude Platform, AWS, Google Cloud, and Microsoft Foundry. Its Opus 5.5 description lists Pro, Max, Team, and Enterprise users, along with Claude Platform, AWS, Google Cloud, and Microsoft Foundry. Check the current product or platform details before choosing based on availability. See Anthropic’s Transparency Hub for its model summary dated October 2, 2026.
Which model is better for everyday use?
For routine work with a clear goal and bounded scope, Sonnet 5.5 is the more economical starting point. Anthropic specifically recommends it for everyday tasks, fixing bugs, and producing polished documents, slides, and spreadsheets. Opus’s higher listed token rates may be justified when a task is ambiguous, open-ended, or benefits from sustained judgment—such as complex coding or document work, or computer use.
Neither description settles the choice for every person or task. If the outcome matters, run a small side-by-side evaluation on representative prompts and judge the results against your own needs: correctness, completeness, amount of editing required, response time, and total API cost. Anthropic cautions that benchmark scores capture only one facet of a model’s capabilities.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What do the published benchmarks show?
Anthropic reports Sonnet 5.5 at 70.6% and Opus 5.5 at 66.4% on Terminal-Bench 4.0. On GDPval-AA v2.1, it reports scores of 1844 for Sonnet and 1846 for Opus. These results differ by evaluation and do not establish a general winner for everyday use or predict performance on an individual workflow.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
