GLM-5.1 vs Grok 4.1 Fast
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Z.ai (Zhipu) · Apr 2026
The April 2026 GLM refresh — the first open-weights model to take #1 on SWE-bench Pro, edging out Claude Opus 4.6.
xAI · Nov 2025
A 2M-token context window for $0.20 per million input tokens — the cheapest long-context frontier offering anywhere.
The verdict
These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 7.8x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 200K for GLM-5.1. And GLM-5.1 is open-weights (MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
Specs & pricing
| GLM-5.1 | Grok 4.1 Fast | |
|---|---|---|
| modhub Index | — | — |
| Input price / 1M | $1.4 | $0.2 |
| Output price / 1M | $4.4 | $0.5 |
| Context window | 200K | 2M |
| Max output | 128K | — |
| Open weights | yes (MIT) | no |
| Reasoning model | yes | yes |
| Multimodal input | text | text, image |
| Knowledge cutoff | Feb 2026 | Nov 2025 |
| Released | Apr 2026 | Nov 2025 |
| Example monthly cost* | $20.60 | $2.75 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, GLM-5.1 or Grok 4.1 Fast?
- These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 7.8x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 200K for GLM-5.1. And GLM-5.1 is open-weights (MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
- Which is cheaper, GLM-5.1 or Grok 4.1 Fast?
- GLM-5.1 costs $1.4/$4.4 per million input/output tokens, while Grok 4.1 Fast costs $0.2/$0.5. For a typical workload of 10M input and 1.5M output tokens per month, that's $20.60 versus $2.75.
- Which model is better for coding, GLM-5.1 or Grok 4.1 Fast?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.