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Claude Opus 5.5 vs Sonnet 5.5: which to use for coding

AutoRouterUpdated 12 min read

Key facts

As of November 10, 2026, start coding work on Claude Opus 5.5, and move a task down to Claude Sonnet 5.5 when it is well scoped: a bug fix, or a feature built against a spec. That is Anthropic's own advice, and Opus 5.5 is Claude Code's default model on every plan. It is also the Claude model for visual work: building an interface from a design, reading charts and screenshots, and animation. Opus 5.5 costs $4 per million input tokens and $20 per million output tokens, twice Sonnet 5.5's $2 and $10. AutoRouter, the Mac app for Codex and Claude Code, wrote this post and worked the prices through: one assumed agent request costs $0.074 on Opus 5.5 and $0.037 on Sonnet 5.5.

Every outside figure below comes from the maker's or publisher's own page, linked where it is used and checked on November 10, 2026.

What is Claude Opus 5.5 good at?

Claude Opus 5.5 is the model Anthropic builds for long-running agentic coding and knowledge work, released on September 22, 2026 as the first of the Claude 5.5 family. Its model page lists multihour coding agents, large-scale refactoring and complex systems engineering among its typical uses. Against Opus 5, its predecessor, Anthropic's announcement says input and output tokens cost 20% less, cache reads cost 60% less, typical workloads cost 40% less at default settings in its own tests, and output arrives more than 30% faster. Claude Sonnet 5.5 followed on September 28, 2026, positioned as the quicker, cheaper companion for well-scoped everyday tasks and bug fixes.

Opus 5.5 does nearly every kind of coding work well, and its visual work stands out. As of November 10, 2026, this is what Anthropic's pages say about it, with one example of our own:

Which coding work belongs on Opus 5.5, and which on Sonnet 5.5?

Complex, open-ended and long-running work belongs on Claude Opus 5.5, and well-scoped work belongs on Claude Sonnet 5.5, most of all when the task comes with a spec and a test that checks the result. That split is Anthropic's. Its guide to choosing a model (November 9, 2026) recommends starting most coding work on Opus 5.5 at medium effort, its guide to building with Sonnet 5.5 puts scoped, checkable tasks on Sonnet 5.5, and its Sonnet 5.5 announcement says Opus 5.5 "remains clearly stronger at complex, open-ended work requiring sustained judgment".

Kind of workStart withWhy (Anthropic's guide, November 9, 2026)
Everyday engineering and debugging, feature work across several pull requestsOpus 5.5 at medium, then highThe guide starts this work on Opus 5.5 for its balance of cost and capability.
A migration or a performance optimizationOpus 5.5 (Fable 5.2 for a major one)The guide says these can have a clear spec and still be too hard for Sonnet 5.5.
Computer use and work heavy on screenshotsOpus 5.5 at mediumThe guide describes these long agentic loops as work Opus 5.5 is built for.
An interface built from a design or screenshot, visual polish, animationOpus 5.5 at medium, then highThe guide starts vision-heavy work on Opus 5.5, and Anthropic's launch post reports its lead on graphics and polish.
A bug fix, feature iteration, work against a specSonnet 5.5 at medium, then highThe guide says Sonnet 5.5 handles scoped tasks well at half Opus 5.5's token price.
Agent tasks you run repeatedly: investigation, review, draftingSonnet 5.5 at mediumThe guide says well-defined, repeated tasks rarely need a bigger model.
You aren't sure yetOpus 5.5 at mediumIt is Claude Code's default model, and Anthropic's models overview says to start there.

Claude Code's cost guide puts the starting point differently: it says Sonnet handles most coding tasks well and reserves Opus for complex architectural decisions and multi-step reasoning. Both pages give complex, multi-step work to Opus. Which model to use for which coding task covers Haiku 5.5, Fable 5.2 and OpenAI's lineup.

How much does Opus 5.5 cost compared with Sonnet 5.5?

Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens as of November 10, 2026, twice Claude Sonnet 5.5's $2 and $10, and the same ratio holds on every line of Anthropic's token price list (pricing).

List price, November 10, 2026Claude Opus 5.5Claude Sonnet 5.5
Input, per million tokens$4$2
5-minute cache write, per million tokens$5$2.50
1-hour cache write, per million tokens$8$4
Cache read, per million tokens$0.20$0.10
Output, per million tokens$20$10
Fast mode, input / output per million tokens$8 / $40Not offered
Default effort on the APImediumhigh
Default effort in Claude Codemediummedium

The example below prices the assumed request AutoRouter's posts use: 45,000 cached input tokens, 5,000 new input tokens written to the 5-minute cache Claude Code uses with an API key, and 2,000 output tokens, thinking included.

One assumed agent request, list prices as of November 10, 2026

Claude Opus 5.5
  45,000 cached input  x  $0.20 per million  =  $0.0090
   5,000 new input     x  $5.00 per million  =  $0.0250  (5-minute cache write)
   2,000 output        x $20.00 per million  =  $0.0400
  Total                                         $0.0740

Claude Sonnet 5.5
  45,000 cached input  x  $0.10 per million  =  $0.0045
   5,000 new input     x  $2.50 per million  =  $0.0125  (5-minute cache write)
   2,000 output        x $10.00 per million  =  $0.0200
  Total                                         $0.0370

At this request size, $20 of API usage pays for 270 requests on Opus 5.5 or 540 on Sonnet 5.5. Every price is doubled, so a finished task costs something other than twice as much only when the two models use different numbers of tokens and steps to finish it.

What does a finished task cost on each model?

A finished task cost 2.2 times as much on Claude Opus 5.5 as on Claude Sonnet 5.5 in AutoRouter's October 28, 2026 measurement of small tasks. On Cursor's harder benchmark tasks it cost between 1.9 and 5.6 times as much at matching effort settings, and Opus 5.5 scored higher at every setting.

Small, well-specified tasks. In What common Claude Code tasks cost, measured on each model, AutoRouter ran five tasks three times each in a 1,176-line Python library on October 28, 2026: a commit message, a rename across files, tests for one module, a failing-test fix and a multi-file refactor. An average run cost $0.110 on Opus 5.5 and $0.049 on Sonnet 5.5 as Claude Code priced them on a Max plan. All 15 runs on each model passed their checks. The study shows what these small tasks cost on each model and that both models finished them. It did not test harder work.

Harder tasks, by effort. CursorBench 4.0, which Cursor runs on ambiguous, multi-file tasks taken from real Cursor sessions, lists both models at every effort level as of November 10, 2026. Cursor computes cost per task from each model's published token prices.

EffortOpus 5.5 scoreOpus 5.5 cost per taskSonnet 5.5 scoreSonnet 5.5 cost per task
low43.7%$1.1735.8%$0.37
medium52.5%$2.9139.2%$0.52
high56.0%$3.9747.8%$1.20
xhigh56.0%$6.9853.1%$2.81
max57.8%$13.4355.5%$7.05

Cursor notes that small differences in its scores may not be statistically meaningful, and Claude Code's docs say effort is calibrated per model, so one level name stands for a different amount of work on each. To price your own work, run one hard task from your backlog on both models and compare what /usage shows.

How do Opus 5.5 and Sonnet 5.5 count against a Claude plan?

Both models draw on the same five-hour and weekly limits of a Claude plan, and Claude Code starts every plan on Opus 5.5 until you change the model. Anthropic says the model you use affects how fast you reach a limit, and doesn't publish by how much, as of November 10, 2026 (plans, usage limits).

How does AutoRouter choose between Opus 5.5 and Sonnet 5.5?

AutoRouter, the Mac app for Codex and Claude Code, picks a model for each task while it is the model selected. Your rules go first. Otherwise AutoRouter works out how hard the task is and only considers models that clear the quality bar for it. Hard work goes to the most capable model your plans cover, even when a cheaper one comes close. Everything else goes to the model that costs you least. Unclear work is never treated as a quick task, and a task that continues keeps its model or moves up. In Claude Code, Claude models run on your Claude plan.

You can choose Opus 5.5 or Sonnet 5.5 in the picker yourself, which sends every request straight to that model, or write a rule in plain English such as "Use Claude Opus 5.5 for UI work." Every request shows its model, what it cost and why. AutoRouter is in beta and sometimes misjudges how hard a task is; you can rate the pick. It earns 10% on paid models and nothing on your plans.

Questions

Is Claude Opus 5.5 better than Sonnet 5.5 at coding?

On complex, open-ended work, yes, by Anthropic's own account: its Sonnet 5.5 announcement says Opus 5.5 is clearly the stronger of the two on work that needs sustained judgment. On CursorBench 4.0, which Cursor runs, Opus 5.5 scored higher than Sonnet 5.5 at every effort level as of November 10, 2026, from 43.7% against 35.8% at low to 57.8% against 55.5% at max. Sonnet 5.5 is the model Anthropic calls strongest at well-scoped everyday tasks, such as fixing a bug.

Should you raise Sonnet 5.5's effort or switch to Opus 5.5?

Raise effort to high first, then switch. Anthropic's guide gives the order: check that the model can verify its own work with a test or a build, raise effort one level, then move to the next model up at a lower effort. Its guide to building with Sonnet 5.5 says Sonnet 5.5 at xhigh or max can lose its balance of quality, speed and cost, and to consider Opus 5.5 then. On SWE-bench Pro, the first guide reports Opus 5.5 at medium scoring about 2.5 points below high for about 70% of the cost.

Is Claude Opus 5.5 good at visual design and animation?

Yes, with direction. Anthropic's launch post reports that Opus 5.5 scored highest among Claude models for graphics and polish in a tester's game build, and its prompting guide says to name the specific styles you don't want, because without direction it falls back on a few defaults. Anthropic publishes no measurement of animation work, as of November 10, 2026. The loop at the top of this post is one example: Opus 5.5 built and animated it in code, in Claude Code.

How do you switch between Opus 5.5 and Sonnet 5.5 in Claude Code?

Run /model sonnet or /model opus in a session. On the Anthropic API the aliases point to Sonnet 5.5 and Opus 5.5, and both start at medium effort (model configuration). Each model has its own prompt cache, so the first request after a switch reads the whole conversation with no cache hits. On the Claude API, a move up to Opus 5.5 keeps the conversation's reasoning and a move down to Sonnet 5.5 loses it. The opusplan alias plans with Opus and carries out the plan with Sonnet. Anthropic's guide notes that this puts code edits on Sonnet, the reverse of its advice, and says to measure it on your own tasks first. How to change the model in Claude Code covers every setting.

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