GLM-4.5-Flash vs Grok 4.1 Fast vs Llama 3.1 Nemotron Ultra 253B
Grok 4.1 Fast comes out ahead, 71 to 65 and 65 on our weighted score.
Z.ai (Zhipu)GLM-4.5-Flash
65/100- ECI—
- PriceFree / Free
- Context131K
- Our pick
xAIGrok 4.1 Fast
71/100- ECI—
- Price$0.20 / $0.50
- Context2M
NVIDIALlama 3.1 Nemotron Ultra 253B
65/100- ECI—
- PriceFree / Free
- Context128K
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 priceGLM-4.5-Flash and Llama 3.1 Nemotron Ultra 253BGLM-4.5-Flash Free · Llama 3.1 Nemotron Ultra 253B 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 FastGLM-4.5-Flash: Text · Grok 4.1 Fast: Text, Images · Llama 3.1 Nemotron Ultra 253B: Text
- Self-hostingLlama 3.1 Nemotron Ultra 253BPublishes downloadable weights
| Measure | Weight | GLM-4.5-Flash | Grok 4.1 Fast | Llama 3.1 Nemotron Ultra 253B |
|---|---|---|---|---|
| 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 | GLM-4.5-FlashZ.ai (Zhipu) | Grok 4.1 FastxAI | Llama 3.1 Nemotron Ultra 253BNVIDIA |
|---|---|---|---|
| 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 Z.AI API | Median of 2 providers | Official Nvidia API |
| Limits | |||
| Context window | 131,072 tokens | 2,000,000 tokens (best) | 128,000 tokens |
| Max output | 98,304 tokens (best) | 30,000 tokens | 8,192 tokens |
| 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 | Proprietary | Proprietary | Open |
| API model ID | glm-4.5-flash | — | nvidia/llama-3.1-nemotron-ultra-253b-v1 |
| API providers | 4 (best) | 2 | 1 |
| Released | Jul 28, 2025 | Nov 19, 2025 | Apr 7, 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.
- GLM-4.5-FlashFree
- Grok 4.1 Fast$3.00
- Llama 3.1 Nemotron Ultra 253BFree
Which should you choose?
Which is better: GLM-4.5-Flash, Grok 4.1 Fast or Llama 3.1 Nemotron Ultra 253B?
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, GLM-4.5-Flash, Grok 4.1 Fast or Llama 3.1 Nemotron Ultra 253B?
GLM-4.5-Flash is cheaper at Free input / Free output per million tokens (official Z.AI API price). Llama 3.1 Nemotron Ultra 253B costs Free input / Free output per million tokens (official Nvidia API price); Grok 4.1 Fast costs $0.20 input / $0.50 output per million tokens (median across 2 API providers). GLM-4.5-Flash is listed as free.
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. GLM-4.5-Flash has not been scored yet, Grok 4.1 Fast has not been scored yet and Llama 3.1 Nemotron Ultra 253B has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for GLM-4.5-Flash, Grok 4.1 Fast and Llama 3.1 Nemotron Ultra 253B 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: GLM-4.5-Flash up to 98,304, Grok 4.1 Fast up to 30,000, Llama 3.1 Nemotron Ultra 253B up to 8,192 tokens.
Which can read images, PDFs, audio or video?
GLM-4.5-Flash accepts text; Grok 4.1 Fast accepts text and images; Llama 3.1 Nemotron Ultra 253B 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; GLM-4.5-Flash and Grok 4.1 Fast 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.
