In short
How they differ.
Worked out from the figures below. Prices and specs are the makers' own, read Oct 20, 2026.
- GPT-6 Luna is cheaper per output token: $0.50 against $4.40 per million tokens, so GLM-5.3 costs 8.8 times as much.
- GPT-6 Luna reads more at once: a context window of 1M tokens against 1M.
- GLM-5.3 can be downloaded and run on your own machine; GPT-6 Luna can't.
- On the 2 independent boards that rank both, each places higher on 1.
Side by side
The specs.
| GLM-5.3 | GPT-6 Luna | |
|---|---|---|
| Made by | Z.ai (Zhipu AI) · China | OpenAI · US |
| Released | Not stated | Sep 22, 2026 |
| Price per 1M tokens | $1.40 in / $4.40 out | $0.10 in / $0.50 out |
| Context window | 1M | 1M |
| Takes in | text | text, image |
| Download and run it yourself | Yes (glm-5.3 (license tag shown on Hugging Face)) | No |
| Size | 753B (Hugging Face safetensors size field) parameters | Not published |
| Maker says | “GLM-5.3 is Z.ai's latest flagship model, delivering comprehensive advancements in complex software engineering” | “Our most efficient model for focused, high-volume tasks.” |
| Sources | Prices, Oct 20, 2026 · Description | Prices, Oct 20, 2026 · Description |
Independent tests
Where they place.
Position on each board we follow (1 is best). Epoch AI's and Vectara's scores are shown; the other boards are linked for their own figures.
| Board | GLM-5.3 | GPT-6 Luna |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | #30155.91 | #27156.31 |
| LMArena Agent ArenaLMArena, Oct 19, 2026 | Not listed | #19 |
| Humanity's Last ExamScale AI | #15 | Not listed |
| SWE-Bench ProScale AI, Sep 22, 2026 | #9 | Not listed |
| Vals IndexVals AI, Oct 19, 2026 | #9 | #19 |
| Terminal-Bench 4.0Vals AI, Oct 19, 2026 | #12 | Not listed |
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