Pick this when
Pinned production that is not ready to move off the 4.x stack.
Skip when
Greenfield work. Sonnet 5 is cheaper and Opus 5 is stronger.
A previous flagship still on the price sheet. Fine to keep. Wrong default for new systems.
Price
- Input / 1M
- $5.00
- Output / 1M
- $25
- Measured task
- $2.10
Still supported. No retirement date announced. Used as Fable 5's safety fallback.
Shape
- Context
- 1M
- Max output
- 32K
- Released
- 2026-03
- Tools
- Yes
- Reasoning
- Yes
Scores
Intelligence index52
GPQA Diamond82
Terminal-Bench 2.168
Agentic index37
- Arena
- 1689
- Speed
- 57/s
- GPQA
- 82.1%
- Term.
- 68.2%
- AA Index. The single number most people mean by “how smart.” It is a blend, so a specialist can lose here and still win the job you care about.
- GPQA. A clean test of hard reasoning. PhD experts sit around 65%. It says little about writing, tools, or taste.
- Term.. Closest public proxy for coding agents that live in a terminal. A high index score with a weak terminal score is a warning.
- Arena. Captures taste and usefulness that unit tests miss. Sample size varies by model, so treat gaps under ~100 Elo as noise.
Anthropic · San Francisco. Claude. Opus 5 leads public intelligence rankings. Fable 5 is the named flagship and the expensive one. Sonnet 5 is the daily driver.