# Nemotron 3 Ultra (550B-A55B)

> NVIDIA's Ultra model scales the Nemotron 3 hybrid stack to 550B total parameters while keeping 55B active per token.

| Property | Value |
| --- | --- |
| Lab | NVIDIA (United States) |
| Released | 2026-06-04 |
| Decoder type | Hybrid MoE |
| Family | Hybrid MoE |
| Scale | 550B total, 55B active (10% active) |
| Context window | 1,000,000 tokens |
| Attention | Mostly Mamba-2 with a few GQA layers |
| Layer mix | 12 GQA + 48 Mamba-2 + 48 MoE |
| KV cache / token (bf16) | 12 KiB (Very low) |
| License | NVIDIA Nemotron Open Model License |

**Key detail:** Scales the latent-MoE hybrid to 108 layers with 48 Mamba-2, 48 latent MoE, and 12 GQA layers.

## Architecture concepts

- [Grouped-Query Attention (GQA)](https://llm-atlas-7or.pages.dev/concepts/gqa.md): Several query heads share one key/value head, shrinking the KV cache with little quality loss.
- [Mixture of Experts (MoE)](https://llm-atlas-7or.pages.dev/concepts/moe.md): Many feed-forward experts, but a router sends each token to only a few of them.
- [Hybrid Attention (Hybrid attention)](https://llm-atlas-7or.pages.dev/concepts/hybrid-attention.md): Mixes cheap linear-attention or state-space layers with a few full-attention layers.

## Benchmark (Artificial Analysis Intelligence Index)

- AA Intelligence Index v5.0: total 11.8 (Knowledge Work 12.9, Coding 0.9, Science 6, General 27.4)
- AA Intelligence Index v4.3.2: total 22.9 (General 34.1, Scientific 15.8, Coding 20.4, Agents 18.5)

## Links

- Architecture diagram: https://sebastianraschka.com/llm-architecture-gallery/images/architectures/nemotron-3-ultra-550b-a55b.webp
- config.json: https://huggingface.co/nvidia/NVIDIA-Nemotron-3-Ultra-550B-A55B-NVFP4/blob/main/config.json
- License: https://www.nvidia.com/en-us/agreements/enterprise-software/nvidia-nemotron-open-model-license/
- Tech report: https://research.nvidia.com/labs/nemotron/files/NVIDIA-Nemotron-3-Ultra-Technical-Report.pdf
- Source card (source of truth): https://sebastianraschka.com/llm-architecture-gallery/#card-nemotron-3-ultra-550b-a55b
- Web page: https://llm-atlas-7or.pages.dev/models/nemotron-3-ultra-550b-a55b/
- JSON: https://llm-atlas-7or.pages.dev/api/models/nemotron-3-ultra-550b-a55b.json

_Data from Sebastian Raschka's LLM Architecture Gallery (https://sebastianraschka.com/llm-architecture-gallery/). Synced 2026-11-04._