Compare AI models
| Specifications | ||
ParametersThe learned values that shape how a model responds. B means billion and T means trillion. For mixture-of-experts models, the total count is larger than the number active for each token. Parameter count alone does not measure quality. | 253B | — |
Context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider. | 128k | 2M |
| These models have no shared benchmark scores. | ||
LiveCodeBenchCompetitive coding — Coding problems published so recently the AI can't have seen them in training — a contamination-free test of raw programming skill. Higher is better. | 66.3% | — |
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 76% | — |
| Overview | ||
| Company | NVIDIA | SpaceXSI |
| Release date | Apr 8 2025 | Sep 19 2025 |
| Access | Open Weight | Closed |
| Model details | View model | View model |
Other comparisons
Llama Nemotron Ultra 253BvsClaude Haiku 5.5Grok 4 FastvsClaude Haiku 5.5Llama Nemotron Ultra 253BvsGPT-6.1 SolGrok 4 FastvsGPT-6.1 SolLlama Nemotron Ultra 253BvsGemini 4 ArgonGrok 4 FastvsGemini 4 ArgonLlama Nemotron Ultra 253BvsMuse Spark OpenGrok 4 FastvsMuse Spark OpenLlama Nemotron Ultra 253BvsDeepSeek-V4.1-Flash-1017Grok 4 FastvsDeepSeek-V4.1-Flash-1017Llama Nemotron Ultra 253BvsMistral Large 4Grok 4 FastvsMistral Large 4Frequently asked questions
Llama Nemotron Ultra 253B and Grok 4 Fast don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Llama Nemotron Ultra 253B shipped 164 days before Grok 4 Fast, so benchmark comparisons should account for the intervening progress.
Context windows are 128k (Llama Nemotron Ultra 253B) vs 2M (Grok 4 Fast). Llama Nemotron Ultra 253B is open weight, while Grok 4 Fast is closed.
Direct benchmark comparisons are unavailable — Llama Nemotron Ultra 253B and Grok 4 Fast don't publish scores on any of the same benchmarks.