GLM-5.1 vs GPT-5.5
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.
OpenAI · Apr 2026
OpenAI's flagship reasoning model with a 1M-token context window, built for hard coding, science and long-horizon agentic work.
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: GLM-5.1 works out roughly 5.2x cheaper per blended million tokens. GPT-5.5 also takes 1M 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 | GPT-5.5 | |
|---|---|---|
| modhub Index | — | 77.2 |
| Input price / 1M | $1.4 | $5 |
| Output price / 1M | $4.4 | $30 |
| Context window | 200K | 1M |
| Max output | 128K | 128K |
| Open weights | yes (MIT) | no |
| Reasoning model | yes | yes |
| Multimodal input | text | text, image |
| Knowledge cutoff | Feb 2026 | Jan 2026 |
| Released | Apr 2026 | Apr 2026 |
| Example monthly cost* | $20.60 | $95.00 |
* 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 GPT-5.5?
- 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: GLM-5.1 works out roughly 5.2x cheaper per blended million tokens. GPT-5.5 also takes 1M 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 GPT-5.5?
- GLM-5.1 costs $1.4/$4.4 per million input/output tokens, while GPT-5.5 costs $5/$30. For a typical workload of 10M input and 1.5M output tokens per month, that's $20.60 versus $95.00.
- Which model is better for coding, GLM-5.1 or GPT-5.5?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.