Grok 4.1 Fast vs GLM-4.5-Flash
Grok 4.1 Fast comes out ahead, 71 to 65 on our weighted score.
- 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
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Make it a three-way comparison.
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). It leads on inputs & features and context window. GLM-4.5-Flash wins on price. 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-FlashGLM-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 tokens
- Widest inputsGrok 4.1 FastGrok 4.1 Fast: Text, Images · GLM-4.5-Flash: Text
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Grok 4.1 Fast | GLM-4.5-Flash |
|---|---|---|---|
| Price | 50% | 76 | 100 |
| Inputs & features | 30% | 60 | 35 |
| Context window | 20% | 72 | 24 |
| Overall | 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 | Grok 4.1 FastxAI | GLM-4.5-FlashZ.ai (Zhipu) |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $0.20 | Free (best) |
| Output | $0.50 | Free (best) |
| Cached input | — | — |
| Blended (3:1) | $0.275 | Free (best) |
| Long-context rate | Same rate | Same rate |
| Price source | Median of 2 providers | Official Z.AI API |
| Limits | ||
| Context window | 2,000,000 tokens (best) | 131,072 tokens |
| Max output | 30,000 tokens | 98,304 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | No |
| PDFs | No | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | No | Yes |
| Tool calling | Yes | Yes |
| Structured output | Yes | No |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | glm-4.5-flash |
| API providers | 2 | 4 (best) |
| Released | 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.
- Grok 4.1 Fast$3.00
- GLM-4.5-FlashFree
Which should you choose?
Which is better: 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). It leads on inputs & features and context window. GLM-4.5-Flash wins on price. 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, Grok 4.1 Fast or GLM-4.5-Flash?
GLM-4.5-Flash is cheaper at 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). GLM-4.5-Flash is listed as free.
Which scores higher on benchmarks?
There is no independent benchmark that covers both models 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 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. Both 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. Maximum output per response: 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?
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?
No. Grok 4.1 Fast and GLM-4.5-Flash are proprietary and only available through APIs and apps.
Which is newer?
Grok 4.1 Fast is the newest, released Nov 19, 2025. GLM-4.5-Flash came out Jul 28, 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.
