Claude Mythos 5.1 vs DeepSeek-V4.1-Flash
Claude Mythos 5.1 and DeepSeek-V4.1-Flash are closely matched at 45.2 and 51.8 on the LLM Stats Score. DeepSeek-V4.1-Flash is 60.6x cheaper per token.
Anthropic · DeepSeek · Updated for 2026
Which is better?
Claude Mythos 5.1 and DeepSeek-V4.1-Flash are closely matched on the overall LLM Stats Score at 45.2 and 51.8.
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.
On price, DeepSeek-V4.1-Flash is roughly 60.6x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
DeepSeek-V4.1-Flash also accepts a larger context window (1,040,000 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 Mythos 5.1
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
Choose DeepSeek-V4.1-Flash
- cost matters — it's about 60.6x cheaper per token
- you process long inputs — it offers a 1,040,000 token context window
- you want the most recent training data — it shipped Sep 2026
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Individual benchmarks
1 reported for Claude Mythos 5.1 · 20 for DeepSeek-V4.1-Flash
Claude Mythos 5.1 outperforms in 1 benchmarks (Terminal-Bench 4.0), while DeepSeek-V4.1-Flash is better at 0 benchmarks.
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 Mythos 5.1 ($10.00/1M tokens) is 45.5x more expensive than DeepSeek-V4.1-Flash ($0.22/1M tokens).
For output processing, Claude Mythos 5.1 ($50.00/1M tokens) is 75.8x more expensive than DeepSeek-V4.1-Flash ($0.66/1M tokens).
In conclusion, Claude Mythos 5.1 is more expensive than DeepSeek-V4.1-Flash.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
DeepSeek-V4.1-Flash accepts 1,040,000 input tokens compared to Claude Mythos 5.1's 1,000,000 tokens. DeepSeek-V4.1-Flash can generate longer responses up to 393,216 tokens, while Claude Mythos 5.1 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Mythos 5.1 and DeepSeek-V4.1-Flash support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Mythos 5.1
DeepSeek-V4.1-Flash
License
Usage and distribution terms
Claude Mythos 5.1 is licensed under a proprietary license, while DeepSeek-V4.1-Flash uses MIT.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
MIT
Open weights
Release Timeline
When each model was launched
Claude Mythos 5.1 was released on 2026-09-01, while DeepSeek-V4.1-Flash was released on 2026-09-10.
DeepSeek-V4.1-Flash is 0 month newer than Claude Mythos 5.1.
Sep 1, 2026
1 weeks ago
Sep 10, 2026
-1 days ago
1w newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
Claude Mythos 5.1 is available from Anthropic. DeepSeek-V4.1-Flash is available from Fireworks, DeepInfra, DeepSeek, Novita.
Claude Mythos 5.1
DeepSeek-V4.1-Flash
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Mythos 5.1 and DeepSeek-V4.1-Flash side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Mythos 5.1 vs DeepSeek-V4.1-Flash.