Head-to-head · Anthropic vs Anthropic
Claude Fable 5.1 vs Claude Opus 5.5
Quick answer: Claude Fable 5.1 stands out for highest quality ceiling in the generally available Claude lineup. Claude Opus 5.5 stands out for matches Claude Fable 5.1 on most work at a much lower price. Reviewed September 2026.
Overview
Claude Fable 5.1: Claude Fable 5.1 is Anthropic's premium generally available model, priced above Opus and built for the hardest reasoning, coding and analysis tasks. Anthropic says the cheaper Opus 5.5 now matches it on most work, so Fable 5.1 makes most sense where the last few points of quality justify the price.
Claude Opus 5.5: Claude Opus 5.5, released on 22 September 2026, is Anthropic's newest Opus model. Anthropic reports it performs at the level of Claude Fable 5.1 on most work while costing about 40% less to run than Opus 5, with a focus on agentic coding, computer use and knowledge work.
At a glance
| Dimension | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Vendor | Anthropic | Anthropic |
| Starting price | API: $10 in / $50 out per M tokens | API: $4 in / $20 out per M tokens |
| Pricing model | Paid | Paid |
| Free tier | No | No |
| Category | Generative AI | Generative AI |
Strengths and limits
Claude Fable 5.1
- Highest quality ceiling in the generally available Claude lineup
- Suited to long, high-stakes analysis
- Heavy prompt caching lowers cost for repeated context
Watch out for
- $10 input and $50 output per million tokens
- Opus 5.5 is comparable on most tasks at lower cost
- Not needed for routine work
Claude Opus 5.5
- Matches Claude Fable 5.1 on most work at a much lower price
- Faster output than Opus 5
- Strong on coding and knowledge work such as financial analysis
Watch out for
- Newest release, so fewer independent long-term evaluations
- Output still costs $20 per million tokens
- Sonnet or Haiku are cheaper for routine tasks
Key features
Claude Fable 5.1
- 1M-token context window at standard pricing
- Top-tier reasoning and agentic performance
- Cache reads priced at a steep discount for repeated context
- Tool use and computer use
- Available through the Claude API and major clouds
Claude Opus 5.5
- 1M-token context window at standard pricing
- Agentic coding, code review and bug detection
- Computer use and complex multi-step tasks
- Clearer, more direct communication style
- Available in Claude apps, the API, Claude Code, AWS, Google Cloud and Microsoft Azure
Pricing compared
Claude Fable 5.1 is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Claude Opus 5.5 is priced by usage rather than by seat: API: $4 in / $20 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Profession-fit verdict
8 roles where both tools are recommended. A higher relevance score means a better fit for that job.
| Profession | Claude Fable 5.1 score | Claude Opus 5.5 score |
|---|---|---|
| Doctor | 8/10 | 9/10 |
| Radiologist | 8/10 | 9/10 |
| Management Consultant | 8/10 | 9/10 |
| Investment Banker | 8/10 | 9/10 |
| Lawyer | 8/10 | 9/10 |
| Compliance Officer | 8/10 | 9/10 |
| Patent Agent | 8/10 | 9/10 |
| College Professor | 8/10 | 9/10 |
Frequently asked questions
Which is better, Claude Fable 5.1 or Claude Opus 5.5?
It depends on the work. Claude Fable 5.1 stands out for highest quality ceiling in the generally available Claude lineup. Claude Opus 5.5 stands out for matches Claude Fable 5.1 on most work at a much lower price. Across 8 professions where both are rated, Claude Opus 5.5 ranks higher more often (8 roles).
How do Claude Fable 5.1 and Claude Opus 5.5 compare on price?
Claude Fable 5.1 is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing. Claude Opus 5.5 is priced by usage rather than by seat: API: $4 in / $20 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Is there a free option between Claude Fable 5.1 and Claude Opus 5.5?
Neither lists a permanent free tier. Look for trials or usage-based pricing to test on real work first.