Claude Haiku 4.5 vs Claude Mythos 5.1
Claude Mythos 5.1 leads the LLM Stats Score 45.3 to 25.7. Claude Haiku 4.5 is 10.0x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Mythos 5.1 leads the overall LLM Stats Score 45.3 to 25.7, ranking #33 overall.
On price, Claude Haiku 4.5 is roughly 10.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Mythos 5.1 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Claude Haiku 4.5
- cost matters — it's about 10.0x cheaper per token
Choose Claude Mythos 5.1
- overall performance matters — it scores 45.3 and ranks #33 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Sep 2026
At a glance
The differences that matter most.
Individual benchmarks
12 reported for Claude Haiku 4.5 · 1 for Claude Mythos 5.1
Claude Haiku 4.5 and Claude Mythos 5.1don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Haiku 4.5 ($1.00/1M tokens) is 10.0x cheaper than Claude Mythos 5.1 ($10.00/1M tokens).
For output processing, Claude Haiku 4.5 ($5.00/1M tokens) is 10.0x cheaper than Claude Mythos 5.1 ($50.00/1M tokens).
In conclusion, Claude Mythos 5.1 is more expensive than Claude Haiku 4.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Mythos 5.1 accepts 1,000,000 input tokens compared to Claude Haiku 4.5's 200,000 tokens. Claude Mythos 5.1 can generate longer responses up to 128,000 tokens, while Claude Haiku 4.5 is limited to 64,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Haiku 4.5 and Claude Mythos 5.1 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Haiku 4.5
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
Claude Haiku 4.5 was released on 2025-10-15, while Claude Mythos 5.1 was released on 2026-09-01.
Claude Mythos 5.1 is 11 months newer than Claude Haiku 4.5.
Oct 15, 2025
11 months ago
Sep 1, 2026
3 weeks ago
10mo newerKnowledge Cutoff
When training data ends
Claude Haiku 4.5 has a documented knowledge cutoff of 2025-02-01, while Claude Mythos 5.1's cutoff date is not specified.
We can confirm Claude Haiku 4.5's training data extends to 2025-02-01, but cannot make a direct comparison without Claude Mythos 5.1's cutoff date.
Feb 2025
—
Provider Availability
Claude Haiku 4.5 is available from Anthropic, DeepInfra, Vertex AI. Claude Mythos 5.1 is available from Anthropic.
Claude Haiku 4.5
Claude Mythos 5.1
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Haiku 4.5 and Claude Mythos 5.1 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Haiku 4.5 vs Claude Mythos 5.1.