Claude Fable 5 vs Claude Sonnet 5.5
Claude Fable 5 and Claude Sonnet 5.5 are closely matched at 53.7 and 58.0 on the LLM Stats Score. Claude Sonnet 5.5 is 5.0x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Fable 5 and Claude Sonnet 5.5 are closely matched on the overall LLM Stats Score at 53.7 and 58.0.
In the 8 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 6; this is a narrower head-to-head signal than the composite indexes.
On price, Claude Sonnet 5.5 is roughly 5.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Claude Fable 5
- you want predictable pricing at $10.00/M input and $50.00/M output
Choose Claude Sonnet 5.5
- your work emphasizes reasoning — it leads those capability indexes
- you value its reported benchmark strengths — it wins 6 of 8 exact shared results
- cost matters — it's about 5.0x cheaper per token
- you want the most recent training data — it shipped Sep 2026
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
19 reported for Claude Fable 5 · 47 for Claude Sonnet 5.5
Claude Fable 5 outperforms in 2 benchmarks (FrontierCode 1.1, Legal Agent Benchmark), while Claude Sonnet 5.5 is better at 6 benchmarks (AutomationBench, BioMysteryBench, DeepSWE 1.1, HealthBench Professional, SWE-Bench Pro, Terminal-Bench 4.0).
Claude Sonnet 5.5 shows notably better performance in the majority of benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Fable 5 ($10.00/1M tokens) is 5.0x more expensive than Claude Sonnet 5.5 ($2.00/1M tokens).
For output processing, Claude Fable 5 ($50.00/1M tokens) is 5.0x more expensive than Claude Sonnet 5.5 ($10.00/1M tokens).
In conclusion, Claude Fable 5 is more expensive than Claude Sonnet 5.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Both models have the same input context window of 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Fable 5 and Claude Sonnet 5.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Fable 5
Claude Sonnet 5.5
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Fable 5 was released on 2026-06-09, while Claude Sonnet 5.5 was released on 2026-09-28.
Claude Sonnet 5.5 is 4 months newer than Claude Fable 5.
Jun 9, 2026
3 months ago
Sep 28, 2026
4 days ago
3mo newerKnowledge Cutoff
When training data ends
Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Claude Fable 5's cutoff date is not specified.
We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Claude Fable 5's cutoff date.
—
Jun 2026
Provider Availability
Claude Fable 5 is available from Anthropic, DeepInfra. Claude Sonnet 5.5 is available from Anthropic.
Claude Fable 5
Claude Sonnet 5.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Fable 5 and Claude Sonnet 5.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Fable 5 vs Claude Sonnet 5.5.