Llama 3.1-405B vs Llama Nemotron Ultra 253B

Llama 3.1-405B (Meta AI) and Llama Nemotron Ultra 253B (NVIDIA) are both frontier AI models. Llama 3.1-405B was published in July 2024 and Llama Nemotron Ultra 253B in March 2025.

Llama Nemotron Ultra 253B was trained on 3.9×10²⁵ FLOP, essentially the same compute as Llama 3.1-405B at 3.8×10²⁵ FLOP. Training compute is the closest available proxy for how much was invested in a model, though it says nothing on its own about how well that compute was spent.

These two models share no benchmark on which both have been scored, so no direct performance comparison is possible here. The specification table below is a comparison of inputs, not of results.