Claude Fable 5.1 vs Claude Mythos 5.1
Claude Fable 5.1 and Claude Mythos 5.1 are closely matched at 56.3 and 45.1 on the LLM Stats Score. Claude Fable 5.1 and Claude Mythos 5.1 cost the same.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Fable 5.1 and Claude Mythos 5.1 are closely matched on the overall LLM Stats Score at 56.3 and 45.1.
In the 1 individual benchmarks reported for both models, Claude Mythos 5.1 wins 1; this is a narrower head-to-head signal than the composite indexes.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Claude Fable 5.1
- you want predictable pricing at $10.00/M input and $50.00/M output
Choose Claude Mythos 5.1
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
At a glance
The differences that matter most.
Individual benchmarks
7 reported for Claude Fable 5.1 · 1 for Claude Mythos 5.1
Claude Fable 5.1 outperforms in 0 benchmarks, while Claude Mythos 5.1 is better at 1 benchmark (Terminal-Bench 4.0).
Claude Mythos 5.1 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Fable 5.1 ($10.00/1M tokens) costs the same as Claude Mythos 5.1 ($10.00/1M tokens).
For output processing, Claude Fable 5.1 ($50.00/1M tokens) costs the same as Claude Mythos 5.1 ($50.00/1M tokens).
In conclusion, Claude Fable 5.1 and Claude Mythos 5.1 cost the same.*
* 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 5.1 and Claude Mythos 5.1 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Fable 5.1
Claude Mythos 5.1
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
Both models were released on 2026-09-01.
They likely represent similar generations of model development.
Sep 1, 2026
1 weeks ago
Sep 1, 2026
1 weeks ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
Claude Fable 5.1 is available from Anthropic. Claude Mythos 5.1 is available from Anthropic.
Claude Fable 5.1
Claude Mythos 5.1
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Fable 5.1 and Claude Mythos 5.1 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Fable 5.1 vs Claude Mythos 5.1.