Claude Opus 5.5 vs Claude Opus 5
Facts only. This page does not pick a winner. For a picked winner, see the use case comparison on Tools.
| Claude Opus 5.5 | Claude Opus 5 | |
|---|---|---|
| API model IDs | claude-opus-5-5 | claude-opus-5 |
| Context window | 1,000,000 | 1,000,000 |
| Lifecycle | active | legacy |
| License | proprietary | proprietary |
| Trains on API data | No | No |
| Zero data retention | on-request | on-request |
| Input per 1M tokens | $4 (verified 2026-11-05) | $5 (verified 2026-11-05) |
Frequently asked questions
- Which has the larger context window, Claude Opus 5.5 or Claude Opus 5?
- Claude Opus 5.5 holds 1,000,000 tokens and Claude Opus 5 holds 1,000,000. Both hold 1,000,000 tokens. The context window counts the prompt, any attached files, and the reply together.
- Which is cheaper, Claude Opus 5.5 or Claude Opus 5?
- Per million input tokens, Claude Opus 5.5 was $4 (verified 2026-11-05) and Claude Opus 5 was $5 (verified 2026-11-05). Claude Opus 5.5 is cheaper per input token. Output tokens cost $20 and $25 respectively, and output volume usually decides the bill.
- Does Claude Opus 5.5 or Claude Opus 5 train on API data?
- Claude Opus 5.5 does not train on API data by default, and Claude Opus 5 does not train on API data by default. Zero data retention is on-request for Claude Opus 5.5 and on-request for Claude Opus 5. Verified 2026-09-08 and 2026-09-08 against the providers' own documentation.
- Is Claude Opus 5.5 or Claude Opus 5 being retired?
- Claude Opus 5.5 is active. Claude Opus 5 is legacy. Lifecycle checked 2026-11-05 and 2026-11-05. Pin a dated snapshot ID rather than an alias if a retirement would break you.