Claude Sonnet vs Opus: What Differs and What It Costs

Quick answer

Sonnet and Opus are two Claude tiers from Anthropic. As of October 7, 2026, its models page lists Sonnet 5.5 at $2 input and $10 output per million tokens and Opus 5.5 at $4 and $20, and its plans page does not list Opus on Free. This site's rule: leave the app default unless one task keeps coming back weak.

Key takeaways

• As of October 7, 2026, Anthropic's models page lists Sonnet 5.5 at $2 per million input tokens and $10 per million output tokens, and Opus 5.5 at $4 and $20.
• What differs on the models page is the listed API price, Anthropic's relative speed label (Fast for Sonnet 5.5, Moderate for Opus 5.5) and what Anthropic says each model is for.
• In the Claude app the model sits in a menu next to the send button, and you can switch it at any point in a chat.
• In the app, a higher effort setting uses your plan's limits faster, and Anthropic says the model you choose also affects how far your usage goes.
• Model names and prices change within months. Check the vendor's page on the day you decide.

What is the difference between Claude Sonnet and Claude Opus?

Sonnet and Opus are two model tiers from Anthropic, the company behind Claude, and Anthropic's own pages position them for different work and price them differently per token. If you are not a developer, our rule of thumb (this site's advice, not Anthropic's) is to leave the model on the default the app picks.

The table below copies the models page's descriptions, speed labels and prices. Names, numbers and prices are those Anthropic's pages showed on October 7, 2026; the line-up changes within months and the page also lists other and older models, so a name in your app may differ.

How do Sonnet and Opus compare on Anthropic's own pages?

On Anthropic's models page as of October 7, 2026, the two differ in what they are described for, how fast they are relative to each other, and the price per token. Both list the same context window. Rows labelled API come from the models page; the app-plans row comes from the plans page, from its row "Opus No Yes Yes Yes Sonnet Yes Yes Yes Yes" under the Free, Pro and Max headings.

Prices in the table are developer (API) rates at the standard rate; Anthropic's pricing page also lists separate caching rates, which are not shown here. Three notes on reading this table. "Latency" is how long you wait for an answer. "Agentic" means the model works through a multi-step job on its own, such as a long coding task. And a "token" is a small piece of text, roughly a word or part of one. "MTok" on the vendor's pages means one million tokens.

This site's arithmetic on the standard listed API rates (4 divided by 2 for input, 20 divided by 10 for output): Opus lists twice the Sonnet price for both input and output. That is a comparison of list prices, not a statement about what you will spend, which depends on how much text goes in and out.

What do the prices mean if I only use the Claude app?

In the app you pay a plan price, not a per-token price, and the model you pick changes how quickly you use your limits. On October 7, 2026, Anthropic's plans page worded the Pro plan this way: "$17 Per month with annual subscription discount ($200 billed up front). $20 if billed monthly." The page shows a dollar sign on that Pro price and names no currency beside it (the developer pricing page says "All prices are in USD" about API prices). It also says "Prices shown don't include applicable tax." and describes Free as "Free for everyone".

On usage, the same page says "Pro gives you at least 5x more usage per 5-hour session than Free." Its models row shows Sonnet on Free, Pro and Max, and Opus on Pro and Max only, so Pro is the lowest plan that lists Opus; the Max plans list it too, and their prices are on the plans page, not quoted here. It adds "Every plan has usage limits that reset on a rolling five-hour session window, and paid plans add weekly limits on top." Prices and plans can change: the page says "Price and plans are subject to change at Anthropic's discretion."

The help center explains the effect on limits in plain terms: "Higher effort means more thorough responses, but they take longer and use more tokens, so you'll reach your usage limits faster." The plans page adds: "How much you can do depends on the length and complexity of your conversations, the model you choose, and the features you use, so there's no fixed message count." That sentence does not say in which direction the model you choose moves your limits, so the dependable way to learn how a model uses yours is to use it for a week.

Where do I choose the model?

In the Claude app, the model sits in a menu next to the send button, and you can change it at any point in a chat. Anthropic's help center says "The model menu next to the send button controls three settings: which Claude model you're chatting with, how much effort it puts into each response, and whether it uses thinking."

To switch, follow these steps.

1. Open a chat and look next to the send button for the model name.
2. Click the name and pick another model from the list. If a model you expect is missing, your plan may not include it, or on an Enterprise plan your administrator may have turned it off.
3. Send your next message. The help center says "Changes apply starting with Claude's next response."
4. Run the same task again on the other model and compare the results side by side before you decide anything.

Each model has a recommended effort level marked as the default in the same menu. Effort is a separate dial from the model: it sets how much work the model puts into one answer.

Do I need to know this?

No, not for everyday tasks: leave the model on the app's default. That rule is this site's reading of Anthropic's help center, which says, in a passage on effort and thinking settings, "For everyday tasks, the defaults work well." The page adds that simple questions, basic information requests and general writing "don't need extra effort or thinking, and lower effort stretches your usage further."

If you do want to see a difference, here is what we suggest watching on your own task, as this site's suggestion and not Anthropic's: how long the answer takes, whether your plan limit runs out sooner, and whether a hard multi-step task comes back the way you need it. Our tip: if limits are the problem, lower the effort setting before you change model, since the help center sentence above ties higher effort to reaching your limits faster.

Move off the default only if one of these is true.

• A task keeps coming back weak after you rewrite your request twice. Try the other tier once on that same task.
• You keep hitting your plan's usage limit and want answers sooner. Compare how fast each tier uses it.
• A developer or vendor who builds software for you asks which model to use. That is the point where the per-token prices matter, because the bill grows with volume.

Anthropic's developer guidance on choosing a model says "Most workloads start with Claude Opus 5.5." Its developer pricing page, in a cost section for building agents, says "Sonnet for most production workloads, and Opus for the most complex reasoning". Anthropic's own developer pages word the starting point differently, and both are guidance for developers using the API, not advice for app users.

In its bullet on the effort parameter, the same page says "Tuning effort is often a better lever than switching models."

When does the choice matter more?

It matters most when you pay per use rather than per month, or when someone sets up an automation that runs the model many times a day. In those cases the price per token times the volume becomes your bill.

For the wider picture of where AI fits in a small business, see our guide to AI automation for small business and AI agents for small business. If a consultant proposes an automation, ask which model it runs on and why. A cheaper tier is a normal, reasonable answer for simple, repeated work, and a higher-priced one is a normal answer for a long, multi-step job. Neither answer is a warning sign by itself.

FAQ

Is Claude Opus better than Sonnet?

This page cannot say, and it uses no benchmark. Anthropic's own pages describe the two for different jobs and list different prices, and the more expensive model is not automatically the right one for a short, ordinary task. Test your own task on both and compare the results.

Is Sonnet cheaper than Opus?

On Anthropic's models page as of October 7, 2026, yes per token: Sonnet 5.5 lists $2 and $10 per million input and output tokens, and Opus 5.5 lists $4 and $20. Those are developer prices. On a Claude subscription you pay the plan price instead, and the model changes how fast you use your limit.

What is the cheapest Claude plan that includes Opus?

On Anthropic's plans page as of October 7, 2026, Opus is not listed on Free and is listed from Pro, which the page words as "$17 Per month with annual subscription discount" or "$20 if billed monthly". The Max plans list Opus too; their prices are on the plans page and are not quoted here.

Do the model names and prices stay the same?

No. Anthropic's models page lists a current line-up plus older models it still offers, and its pricing page says price and plans can change at Anthropic's discretion. Treat any name or price on a third-party page, including this one, as a snapshot.

How this page was made

This page was drafted with Claude, an AI model made by Anthropic, and checked against each vendor's published material on October 7, 2026. Every model name, price and quotation comes from Anthropic's own models, pricing and help pages, opened on that day; no third-party review or benchmark was used. Anthropic's statements are reported as its own and are not independently tested here. We compare only Sonnet and Opus and ran no speed or quality test, so a table of documented differences cannot tell you which tier suits your tasks. Plans, models and prices change often; check the linked pages before you decide.