Claude Opus 4.8

Claude Opus 4.8 is listed as legacy — still active, no longer receiving updates, and liable to be deprecated in future. It matters more than most legacy models for one reason: it is the recommended replacement named against several already-retired models, including Claude Opus 4.1, Claude Opus 4 and Claude Opus 3.

If you followed a migration notice in the last year, this is probably where you landed. The next hop is Claude Opus 5, which costs the same.

Why you would still be on it

• Identical pricing to Opus 5 ($5 in / $25 out), so cost is not a reason to stay or move.
• On Opus 4.8 the effort parameter defaults to high on all surfaces, including claude.ai — broader than Opus 5, where the high default applies to the Claude API and Claude Code.
• Fast mode supports Opus 4.8, at the same $10 / $50 premium rate as Opus 5.

Specifications

Property	Value
Claude API ID	claude-opus-4-8
Context window	1M tokens
Max output	128K tokens
Adaptive thinking	Yes
Extended thinking parameter	No
Reliable knowledge cutoff	January 2026

Lifecycle

Active but legacy. Tentative retirement not sooner than 28 May 2027.