Llama 3.1 Nemotron Ultra 253B vs Grok 4.1 Fast vs GLM-4.5-Flash
Grok 4.1 Fast comes out ahead, 71 to 65 and 65 on our weighted score.
NVIDIALlama 3.1 Nemotron Ultra 253B
65/100- ECI—
- PriceFree / Free
- Context128K
- Our pick
xAIGrok 4.1 Fast
71/100- ECI—
- Price$0.20 / $0.50
- Context2M
Z.ai (Zhipu)GLM-4.5-Flash
65/100- ECI—
- PriceFree / Free
- Context131K
Grok 4.1 Fast is our pick
Grok 4.1 Fast is the better all-round choice, scoring 71/100 against GLM-4.5-Flash (65) and Llama 3.1 Nemotron Ultra 253B (65). It leads on inputs & features and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceLlama 3.1 Nemotron Ultra 253B and GLM-4.5-FlashLlama 3.1 Nemotron Ultra 253B Free · GLM-4.5-Flash Free · Grok 4.1 Fast $0.275 per 1M tokens (3:1 blend)
- Longest contextGrok 4.1 FastGrok 4.1 Fast 2,000,000 · GLM-4.5-Flash 131,072 · Llama 3.1 Nemotron Ultra 253B 128,000 tokens
- Widest inputsGrok 4.1 FastLlama 3.1 Nemotron Ultra 253B: Text · Grok 4.1 Fast: Text, Images · GLM-4.5-Flash: Text
- Self-hostingLlama 3.1 Nemotron Ultra 253BPublishes downloadable weights
| Measure | Weight | Llama 3.1 Nemotron Ultra 253B | Grok 4.1 Fast | GLM-4.5-Flash |
|---|---|---|---|---|
| Price | 50% | 100 | 76 | 100 |
| Inputs & features | 30% | 35 | 60 | 35 |
| Context window | 20% | 24 | 72 | 24 |
| Overall | 100% | 65/100 | 71/100 | 65/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Llama 3.1 Nemotron Ultra 253BNVIDIA | Grok 4.1 FastxAI | GLM-4.5-FlashZ.ai (Zhipu) |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | Free (best) | $0.20 | Free (best) |
| Output | Free (best) | $0.50 | Free (best) |
| Cached input | — | — | — |
| Blended (3:1) | Free (best) | $0.275 | Free (best) |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Nvidia API | Median of 2 providers | Official Z.AI API |
| Limits | |||
| Context window | 128,000 tokens | 2,000,000 tokens (best) | 131,072 tokens |
| Max output | 8,192 tokens | 30,000 tokens | 98,304 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | No | Yes | No |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yes | No | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | Yes | No |
| Availability | |||
| Weights | Open | Proprietary | Proprietary |
| API model ID | nvidia/llama-3.1-nemotron-ultra-253b-v1 | — | glm-4.5-flash |
| API providers | 1 | 2 | 4 (best) |
| Released | Apr 7, 2025 | Nov 19, 2025 | Jul 28, 2025 |
| Knowledge cutoff | — | — | Apr 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Llama 3.1 Nemotron Ultra 253BFree
- Grok 4.1 Fast$3.00
- GLM-4.5-FlashFree
Which should you choose?
Which is better: Llama 3.1 Nemotron Ultra 253B, Grok 4.1 Fast or GLM-4.5-Flash?
Grok 4.1 Fast is the better all-round choice, scoring 71/100 against GLM-4.5-Flash (65) and Llama 3.1 Nemotron Ultra 253B (65). It leads on inputs & features and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Llama 3.1 Nemotron Ultra 253B, Grok 4.1 Fast or GLM-4.5-Flash?
Llama 3.1 Nemotron Ultra 253B is cheaper at Free input / Free output per million tokens (official Nvidia API price). GLM-4.5-Flash costs Free input / Free output per million tokens (official Z.AI API price); Grok 4.1 Fast costs $0.20 input / $0.50 output per million tokens (median across 2 API providers). Llama 3.1 Nemotron Ultra 253B is listed as free.
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Llama 3.1 Nemotron Ultra 253B has not been scored yet, Grok 4.1 Fast has not been scored yet and GLM-4.5-Flash has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Llama 3.1 Nemotron Ultra 253B, Grok 4.1 Fast and GLM-4.5-Flash yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Grok 4.1 Fast has the largest context window at 2,000,000 tokens, against 131,072 for GLM-4.5-Flash and 128,000 for Llama 3.1 Nemotron Ultra 253B. Maximum output per response: Llama 3.1 Nemotron Ultra 253B up to 8,192, Grok 4.1 Fast up to 30,000, GLM-4.5-Flash up to 98,304 tokens.
Which can read images, PDFs, audio or video?
Llama 3.1 Nemotron Ultra 253B accepts text; Grok 4.1 Fast accepts text and images; GLM-4.5-Flash accepts text. Grok 4.1 Fast handles the widest range of inputs.
Are any of these open source?
Llama 3.1 Nemotron Ultra 253B publishes its weights and can be self-hosted; Grok 4.1 Fast and GLM-4.5-Flash is proprietary.
Which is newer?
Grok 4.1 Fast is the newest, released Nov 19, 2025. GLM-4.5-Flash came out Jul 28, 2025; Llama 3.1 Nemotron Ultra 253B came out Apr 7, 2025. Knowledge cutoff: GLM-4.5-Flash Apr 2025.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
