Models · · 2 min read

Anthropic ships Claude Opus 4.8 — same price as 4.7, but the cache and fast-mode math changed underneath

Claude Opus 4.8 launched May 28, 2026 at the same $5/$25 list price as 4.7. Benchmark gains are single-digit (SWE-Bench Pro 64.3% → 69.2%), but the real shifts are a 4× lower prompt-cache minimum, 3× cheaper fast mode, mid-conversation system messages, and Dynamic Workflows in Claude Code.

Anthropic released Claude Opus 4.8 on May 28, 2026, calling it “a modest but tangible improvement” — unusually honest framing for a model launch. The list price is unchanged from Opus 4.5, 4.6, and 4.7: $5 / $25 per million input/output tokens.

The benchmark gains are real but single-digit: agentic coding (SWE-Bench Pro) rose from 64.3% to 69.2%, and agentic computer use (OSWorld-Verified) from 82.8% to 83.4%. GPT-5.5 still edges it on terminal coding (78.2% vs 74.6%).

Anthropic's official benchmark chart comparing Claude Opus 4.8 against Opus 4.7, GPT-5.5, and Gemini 3.1 Pro across six agentic tasks
Official benchmark comparison: Opus 4.8 leads on coding, computer use, reasoning, and knowledge work — by single-digit margins. (Source: Anthropic)

The numbers aren’t the story. Four under-the-fold changes matter more for builders:

  • Prompt-cache minimum dropped 4× — from 4,096 to 1,024 tokens, pulling small production agents into the 10× cache-hit discount.
  • Fast mode is 3× cheaper — $10 / $50 per million (was $30 / $150), making real-time agents economically viable.
  • Mid-conversation system messages — update instructions mid-loop without breaking the prompt cache.
  • Dynamic Workflows in Claude Code — hundreds of parallel subagents for codebase-scale migrations (Enterprise / Team / Max only).

Opus 4.8 is also 4× less likely than 4.7 to let flaws in its own code pass unflagged — a reliability win that benchmark tables don’t capture.

One gotcha for API users: the model ID is claude-opus-4-8 with dashes, not a dot. In Claude Code you need v2.1.154+ (claude update, then /model) before 4.8 appears.

Full builder breakdown: the 4 changes that actually matter. Step-by-step switching guide for every surface: how to switch to Opus 4.8.

Source: Anthropic