Claude Mythos 5.1 vs Nemotron 3 Ultra (550B A55B)
Claude Mythos 5.1 leads the LLM Stats Score 45.1 to 36.3. Nemotron 3 Ultra (550B A55B) is 21.6x cheaper per token.
Anthropic · NVIDIA · Updated for 2026
Which is better?
Claude Mythos 5.1 leads the overall LLM Stats Score 45.1 to 36.3, ranking #33 overall.
On price, Nemotron 3 Ultra (550B A55B) is roughly 21.6x 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 Mythos 5.1
- overall performance matters — it scores 45.1 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
Choose Nemotron 3 Ultra (550B A55B)
- cost matters — it's about 21.6x cheaper per token
- 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 · 26 for Nemotron 3 Ultra (550B A55B)
Claude Mythos 5.1 and Nemotron 3 Ultra (550B A55B)don'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 Mythos 5.1 ($10.00/1M tokens) is 20.0x more expensive than Nemotron 3 Ultra (550B A55B) ($0.50/1M tokens).
For output processing, Claude Mythos 5.1 ($50.00/1M tokens) is 22.7x more expensive than Nemotron 3 Ultra (550B A55B) ($2.20/1M tokens).
In conclusion, Claude Mythos 5.1 is more expensive than Nemotron 3 Ultra (550B A55B).*
* 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 Nemotron 3 Ultra (550B A55B)'s 262,144 tokens. Nemotron 3 Ultra (550B A55B) can generate longer responses up to 262,144 tokens, while Claude Mythos 5.1 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Claude Mythos 5.1 supports multimodal inputs, whereas Nemotron 3 Ultra (550B A55B) does not.
Claude Mythos 5.1 can handle both text and other forms of data like images, making it suitable for multimodal applications.
Claude Mythos 5.1
Nemotron 3 Ultra (550B A55B)
License
Usage and distribution terms
Claude Mythos 5.1 is licensed under a proprietary license, while Nemotron 3 Ultra (550B A55B) uses OpenMDW License v1.1.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
OpenMDW License v1.1
Open weights
Release Timeline
When each model was launched
Claude Mythos 5.1 was released on 2026-09-01, while Nemotron 3 Ultra (550B A55B) was released on 2026-06-04.
Claude Mythos 5.1 is 3 months newer than Nemotron 3 Ultra (550B A55B).
Sep 1, 2026
2 weeks ago
2mo newerJun 4, 2026
3 months ago
Knowledge Cutoff
When training data ends
Nemotron 3 Ultra (550B A55B) has a documented knowledge cutoff of 2025-09-30, while Claude Mythos 5.1's cutoff date is not specified.
We can confirm Nemotron 3 Ultra (550B A55B)'s training data extends to 2025-09-30, but cannot make a direct comparison without Claude Mythos 5.1's cutoff date.
—
Sep 2025
Provider Availability
Claude Mythos 5.1 is available from Anthropic. Nemotron 3 Ultra (550B A55B) is available from DeepInfra.
Claude Mythos 5.1
Nemotron 3 Ultra (550B A55B)
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Mythos 5.1 and Nemotron 3 Ultra (550B A55B) side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Mythos 5.1 vs Nemotron 3 Ultra (550B A55B).