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. | ||
BullshitBench v2Nonsense detection — Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | — | 19% |
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 | Nov 19 2025 |
| Access | Open Weight | Closed |
| Model details | View model | View model |
Other comparisons
Llama Nemotron Ultra 253BvsClaude Haiku 5.5Grok 4.1 FastvsClaude Haiku 5.5Llama Nemotron Ultra 253BvsGPT-6.1 SolGrok 4.1 FastvsGPT-6.1 SolLlama Nemotron Ultra 253BvsGemini 4 ArgonGrok 4.1 FastvsGemini 4 ArgonLlama Nemotron Ultra 253BvsMuse Spark OpenGrok 4.1 FastvsMuse Spark OpenLlama Nemotron Ultra 253BvsDeepSeek-V4.1-Flash-1017Grok 4.1 FastvsDeepSeek-V4.1-Flash-1017Llama Nemotron Ultra 253BvsMistral Large 4Grok 4.1 FastvsMistral Large 4Frequently asked questions
Llama Nemotron Ultra 253B and Grok 4.1 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 225 days before Grok 4.1 Fast, so benchmark comparisons should account for the intervening progress.
Context windows are 128k (Llama Nemotron Ultra 253B) vs 2M (Grok 4.1 Fast). Llama Nemotron Ultra 253B is open weight, while Grok 4.1 Fast is closed.
Direct benchmark comparisons are unavailable — Llama Nemotron Ultra 253B and Grok 4.1 Fast don't publish scores on any of the same benchmarks.