Claude Opus 4.5 (20251101)

Best-supported use cases

• Homework and maths: not ranked, because there is not enough data for the main test.
• Research and checking facts: not ranked, because there is not enough data for the main test.

Where an alternative might be more suitable

• Writing and creating content: rated Strong on writing votes. Compare it with Claude Opus 5.5, the best-supported choice for this task.
• Coding and building things: rated Strong on coding votes. Compare it with Claude Opus 5.5, the best-supported choice for this task.
• Homework and maths: no result on hard maths problems, so we cannot say. See which models the evidence does support.
• Business emails and everyday work: rated Strong on business-task votes. Compare it with Gemini 4 Argon, the best-supported choice for this task.
• Research and checking facts: no result on short factual questions, so we cannot say. See which models the evidence does support.

What it is

Maker

Anthropic

Access, as listed by Epoch AI

Not stated

Licence, as listed by Arena

Proprietary

Last observation in our data

28 Oct 2026

Data last changed

29 Oct 2026, 14:36 UTC

We have not verified an official product page for this model, so we do not link to one.

How you can use it

Proprietary. The model's files are not published, so it is generally available only through its maker or partners the maker chooses.

How you can reach it (an app, a website, a developer API or a third-party tool) and what that costs are not covered by our benchmark data. Where we could verify prices from the maker's own pages, they are shown under Price. See models, apps and harnesses and how AI pricing works.

Price

Price not independently verified

What Anthropic's own page says about the Opus family (USD ($ as shown; the page does not state a currency code); checked 28 Oct 2026)

• Free ($0): Opus not available
• Pro ($20 per month billed monthly, or $17 per month billed annually ($200 up front)): Opus available
• Max (From $100 per month): Opus available

The page marks plans against model families, not versions, so it does not say which version of a family a plan includes. Check that before relying on it.

See Claude plans and pricing (checked 28 Oct 2026). Page opened and read.

We never infer subscription prices from API prices. New to “tokens” and “per million”? See how AI pricing works.

Good to remember

• Benchmarks are samples of tasks. None proves performance in every situation.
• Arena scores come from people choosing between answers. That measures preference, not correctness.
• Ratings are relative to the 77 models listed here. A different set would change them.
• Sources test models at different settings. Each result shows the setting used, and we do not adjust it.