Claude Haiku 5.5 vs Claude Mythos Preview
Claude Haiku 5.5 and Claude Mythos Preview are closely matched at 50.3 and 54.5 on the LLM Stats Score. Claude Haiku 5.5 is 250.0x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Haiku 5.5 and Claude Mythos Preview are closely matched on the overall LLM Stats Score at 50.3 and 54.5.
In the 3 individual benchmarks reported for both models, Claude Mythos Preview wins 3; this is a narrower head-to-head signal than the composite indexes.
On price, Claude Haiku 5.5 is roughly 250.0x 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 Haiku 5.5
- cost matters — it's about 250.0x cheaper per token
Choose Claude Mythos Preview
- your work emphasizes reasoning — it leads those capability indexes
- you value its reported benchmark strengths — it wins 3 of 3 exact shared results
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
36 reported for Claude Haiku 5.5 · 16 for Claude Mythos Preview
Claude Haiku 5.5 outperforms in 0 benchmarks, while Claude Mythos Preview is better at 3 benchmarks (SWE-bench Multilingual, SWE-Bench Multimodal, SWE-Bench Pro).
Claude Mythos Preview 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 Haiku 5.5 ($0.10/1M tokens) is 250.0x cheaper than Claude Mythos Preview ($25.00/1M tokens).
For output processing, Claude Haiku 5.5 ($0.50/1M tokens) is 250.0x cheaper than Claude Mythos Preview ($125.00/1M tokens).
In conclusion, Claude Mythos Preview is more expensive than Claude Haiku 5.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Only Claude Haiku 5.5 specifies input context (1,000,000 tokens). Only Claude Haiku 5.5 specifies output context (128,000 tokens).
Input capabilities
Documented input modalities across available providers
Both Claude Haiku 5.5 and Claude Mythos Preview support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Haiku 5.5
Claude Mythos Preview
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 Haiku 5.5 was released on 2026-10-07, while Claude Mythos Preview's release date is not specified.
We can confirm Claude Haiku 5.5's release timeline, but cannot make a direct age comparison without Claude Mythos Preview's release date.
Oct 7, 2026
0 days ago
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Knowledge Cutoff
When training data ends
Claude Haiku 5.5 has a documented knowledge cutoff of 2026-06-01, while Claude Mythos Preview's cutoff date is not specified.
We can confirm Claude Haiku 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Claude Mythos Preview's cutoff date.
Jun 2026
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Provider Availability
Claude Haiku 5.5 is available from Anthropic. Claude Mythos Preview is available from Anthropic.
Claude Haiku 5.5
Claude Mythos Preview
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Haiku 5.5 and Claude Mythos Preview side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Haiku 5.5 vs Claude Mythos Preview.