Claude Mythos 5.2 vs Claude Opus 5.5
Claude Mythos 5.2 and Claude Opus 5.5 are closely matched at 59.6 and 58.9 on the LLM Stats Score. Claude Opus 5.5 is 2.0x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Mythos 5.2 and Claude Opus 5.5 are closely matched on the overall LLM Stats Score at 59.6 and 58.9.
In the 3 individual benchmarks reported for both models, Claude Mythos 5.2 wins 3; this is a narrower head-to-head signal than the composite indexes.
On price, Claude Opus 5.5 is roughly 2.0x 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 Mythos 5.2
- you value its reported benchmark strengths — it wins 3 of 3 exact shared results
- you want the most recent training data — it shipped Nov 2026
Choose Claude Opus 5.5
- cost matters — it's about 2.0x cheaper per token
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
9 reported for Claude Mythos 5.2 · 32 for Claude Opus 5.5
Claude Mythos 5.2 outperforms in 3 benchmarks (LatchBio SingleCellBench, Terminal-Bench 4.0, Terminal-Bench-Science 0.1), while Claude Opus 5.5 is better at 0 benchmarks.
Claude Mythos 5.2 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 Mythos 5.2 ($8.00/1M tokens) is 2.0x more expensive than Claude Opus 5.5 ($4.00/1M tokens).
For output processing, Claude Mythos 5.2 ($40.00/1M tokens) is 2.0x more expensive than Claude Opus 5.5 ($20.00/1M tokens).
In conclusion, Claude Mythos 5.2 is more expensive than Claude Opus 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 Mythos 5.2 and Claude Opus 5.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Mythos 5.2
Claude Opus 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 Mythos 5.2 was released on 2026-11-09, while Claude Opus 5.5 was released on 2026-09-22.
Claude Mythos 5.2 is 2 months newer than Claude Opus 5.5.
Nov 9, 2026
0 days ago
1mo newerSep 22, 2026
1 months ago
Knowledge Cutoff
When training data ends
Both models have the same knowledge cutoff date of 2026-06-01.
They should have similar awareness of historical events and information up to this date.
Jun 2026
Jun 2026
Provider Availability
Claude Mythos 5.2 is available from Anthropic. Claude Opus 5.5 is available from Anthropic.
Claude Mythos 5.2
Claude Opus 5.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Mythos 5.2 and Claude Opus 5.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Mythos 5.2 vs Claude Opus 5.5.