GPT-5.6 Luna vs GLM 5.3
GLM 5.3 is 1.1× cheaper for typical traffic ; GLM 5.3 scores higher on the Artificial Analysis intelligence index (44.8 vs 37.3).
Prices checked Oct 21, 2026
| GPT-5.6 Luna | GLM 5.3 | |
|---|---|---|
| Developer | OpenAI | Z.ai |
| Input / 1M tokens | $0.20 | $0.079 |
| Output / 1M tokens | $1.20 | $1.40 |
| Cached input / 1M | $0.02 | $0.078 |
| Context window | 1.05M | 1.05M |
| Max output | 128K | 944K |
| Intelligence index | 37.3 | 44.8 |
| Image input | Yes | No |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
| Open weights | No | Yes |
Monthly cost for common workloads
| Workload | GPT-5.6 Luna | GLM 5.3 |
|---|---|---|
| Customer chatbot 1,000 conversations a day, 8 turns each | $134 | $146 |
| Document Q&A (RAG) 500 questions a day over retrieved documents | $25.38 | $17.60 |
| Coding / tool-using agent 200 tasks a day, long tool-heavy contexts | $52.20 | $61.77 |
| Content generation 30 long articles a day | $3.24 | $3.36 |
| Classification / extraction 100,000 short items a day | $234 | $134 |
Estimates include cached-input discounts where a model offers them. Try your own numbers in the cost calculator.
Which one to choose
- Lowest cost: GLM 5.3 — 1.1× cheaper on a 3:1 input/output mix.
- Longer documents: GPT-5.6 Luna reads up to 1.05M tokens at once.
- Capabilities: GPT-5.6 Luna — vision, tools, reasoning, JSON; GLM 5.3 — tools, reasoning, JSON, open weights.