Claude Fable 5.1 vs Claude Sonnet 5.5
Compare Claude Fable 5.1 vs Claude Sonnet 5.5 API pricing, token costs, context windows, and latency. See which model is cheaper and better for your stack.
Claude Fable 5.1 charges $10.00/1M input and $50.00/1M output tokens, compared to Claude Sonnet 5.5 at $2.00/1M input and $10.00/1M output. Claude Sonnet 5.5 is 5.0x cheaper on input tokens. In reasoning benchmarks, Claude Sonnet 5.5 holds the higher AA Intelligence Index rating (55/100). For latency-critical streaming, Claude Fable 5.1 delivers 88 t/s (155.0s TTFT) while Claude Sonnet 5.5 provides 156 t/s (247.0s TTFT).
Full Metric & Specification Comparison
| Metric | Claude Fable 5.1 | Claude Sonnet 5.5 | Advantage |
|---|---|---|---|
| Provider | Anthropic | Anthropic | - |
| Input Token Cost (1M) | $10.000 | $2.000 | Claude Sonnet 5.5 |
| Output Token Cost (1M) | $50.000 | $10.000 | Claude Sonnet 5.5 |
| Context Window | 1,000k tokens | 1,000k tokens | Tie |
| AA Intelligence Index | 49/100 | 55/100 | Claude Sonnet 5.5 |
| Streaming Latency | Moderate | Fast | - |
Key Architectural Takeaways
- Input Token Cost: Claude Fable 5.1 is $10.00/1M vs Claude Sonnet 5.5 at $2.00/1M
- Output Token Cost: Claude Fable 5.1 is $50.00/1M vs Claude Sonnet 5.5 at $10.00/1M
- Context Window: Claude Fable 5.1 supports 1,000k tokens vs Claude Sonnet 5.5 with 1,000k tokens
- Benchmark Intelligence Rating: Claude Fable 5.1 scores 49/100 vs Claude Sonnet 5.5 at 55/100 (AA Index v5)
- Inference Latency: Claude Fable 5.1 is rated Moderate vs Claude Sonnet 5.5 rated Fast
Calculate Your Team's Exact Bill Difference
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Deploying Claude Sonnet 5.5 over Claude Fable 5.1 saves $420.00/mo ($5040/yr) at this volume.
Frequently Asked Questions
Is Claude Fable 5.1 cheaper than Claude Sonnet 5.5?
Claude Sonnet 5.5 is significantly more economical, charging $2.00/1M input compared to $10.00/1M for Claude Fable 5.1.
Which model should I choose for production?
If your primary constraint is API cost and high query throughput, choose Claude Sonnet 5.5. If you require peak reasoning accuracy and complex tool use, Claude Sonnet 5.5 is recommended.
How does context window compare between Claude Fable 5.1 and Claude Sonnet 5.5?
Claude Fable 5.1 offers the larger context window (1,000k tokens), allowing you to pass significantly larger codebases or documents without chunking.
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