Claude Fable 5 vs Claude Sonnet 5.5
Side-by-side comparison using current list prices and the live leaderboard.
Verdict
Claude Sonnet 5.5 is 5x cheaper per input token.
- Claude Fable 5 is #1 on the LMRank leaderboard; Claude Sonnet 5.5 is not ranked yet.
- Claude Sonnet 5.5 is 5x cheaper per input token ($2.00 vs $10.00 per 1M).
- Both have a 1M-token context window.
At a Glance
| Attribute | Claude Fable 5 | Claude Sonnet 5.5 |
|---|---|---|
| Lab | Anthropic | Anthropic |
| Leaderboard rank | #1 | Not ranked yet |
| Tags | Long Context Coding Intelligent Reasoning Agentic | Long Context Coding Intelligent Image Input Reasoning Agentic |
| Context | 1M tokens | 1M tokens |
| Input price | $10.00/1M | $2.00/1M |
| Output price | $50.00/1M | $10.00/1M |
| Input modalities | Image and text | Text, image, and file |
| Output modalities | Text | Text |
Claude Fable 5: strengths
- #1 Intelligence Index at 64.9
- 1M-token context window
- 95% on SWE-bench Verified
- Strong agentic and coding performance
- Vision and scientific research capable
Claude Sonnet 5.5: strengths
- Direct upgrade over Sonnet 5 for well-scoped everyday work
- Strong at building features and fixing bugs in existing codebases
- 1M-token context window covers large multi-file tasks
- $2/$10 per M pricing, well below Opus-class flagships
Claude Fable 5: weaknesses
- Safety fallback reduces capability on sensitive queries
- Access may still be capacity-constrained after the June 2026 suspension
- High cost: $10/$50 per million tokens
- Mandatory 30-day data retention
Claude Sonnet 5.5: weaknesses
- Below Opus 5.5 on demanding reasoning and long-horizon agents
- Mid-tier positioning means heavier tasks still need Opus
Claude Fable 5: best for
- Autonomous agentic workflows
- Long-horizon software engineering
- Complex knowledge work and research
- Multi-step tool-use with verifiable chain-of-thought
Claude Sonnet 5.5: best for
- Everyday coding assistance and code review
- Bug fixing in large existing codebases
- Cost-aware agentic coding workflows