Model board / Claude Opus 5.5

Verified 2026-09-24 against the pages listed below. Prices are USD per 1M tokens, list rate — no committed-use, enterprise or volume discount.

1h cache write $8.00; fast mode $8/$40. Cache reads bill at 0.05x input — half the 0.1x Opus 5 and every earlier Opus pays

full 1M window at standard rates; up to 300K output on the Batch API with a beta header

read 0.05x input; 5m write 1.25x, 1h write 2x

Watch out

Not a drop-in swap for Opus 5. Thinking cannot be disabled (400), forced tool_choice any/tool returns 400, the default effort drops from high to medium, and text between tool calls now arrives in thinking blocks. It also ships safety classifiers that decline with HTTP 200 and stop_reason "refusal", as the Fable line does

What we would use it for

Anthropic's recommended starting point for most work — long agentic coding and knowledge work, a fifth cheaper than Opus 5 on every column

What this has cost, week by week

Output price at each refresh since 2026-09-24. A vendor change is the provider changing its price. Our correction means this board changed what it prints and the provider's charge did not move — the two are never merged, because publishing the second as the first would be a price rise that never happened.

Nothing has moved since we started tracking it.

Where these numbers came from

• https://platform.claude.com/docs/en/about-claude/pricing
• https://platform.claude.com/docs/en/about-claude/models/overview
• https://platform.claude.com/docs/en/build-with-claude/prompt-caching
• https://platform.claude.com/docs/en/models/opus-5-5/overview
• https://platform.claude.com/docs/en/release-notes/overview

No number on this page was written that was not read from one of those pages on 2026-09-24. If one is wrong, send us the source URL and it is corrected in the next weekly refresh, with a changelog line saying what was wrong — contact@naderu.com.

Jobs this is one of our picks for

• Code review — Read a diff or a repository and say what is wrong (code-review)

Discussed in Naderu Weekly

• Three launches, no price rises — 2026-09-24

The rest of the board

This row sits alongside 64 others on the model board, refreshed every week. The same data as JSON, and the terms for using it, are at /board-data.