In short
How they differ.
Worked out from the figures below. Prices and specs are the makers' own, read Oct 20, 2026.
- Gemini 3.8 Flash is cheaper per output token: $3.75 against $4.40 per million tokens, so GLM-5.3 costs 1.2 times as much.
- Gemini 3.8 Flash reads more at once: a context window of 1M tokens against 1M.
- GLM-5.3 can be downloaded and run on your own machine; Gemini 3.8 Flash can't.
- On the 4 independent boards that rank both, each places higher on 2.
Side by side
The specs.
| Gemini 3.8 Flash | GLM-5.3 | |
|---|---|---|
| Made by | Google · US | Z.ai (Zhipu AI) · China |
| Released | Sep 2, 2026 | Not stated |
| Price per 1M tokens | $0.75 in / $3.75 out (introductory price) | $1.40 in / $4.40 out |
| Context window | 1M | 1M |
| Takes in | text, image, video, audio, pdf | text |
| Download and run it yourself | No | Yes (glm-5.3 (license tag shown on Hugging Face)) |
| Size | Not published | 753B (Hugging Face safetensors size field) parameters |
| Maker says | “Gemini 3.8 Flash is our most intelligent Flash model, engineered for long-horizon software engineering, autonomous agents, and complex enterprise workflows—all with the speed and cost efficiency of Flash.” | “GLM-5.3 is Z.ai's latest flagship model, delivering comprehensive advancements in complex software engineering” |
| 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 | Gemini 3.8 Flash | GLM-5.3 |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | #19157.2 | #30155.91 |
| LMArena textLMArena, Oct 15, 2026 | #9 | Not listed |
| LMArena creative writingLMArena, Oct 15, 2026 | #7 | Not listed |
| LMArena mathLMArena, Oct 15, 2026 | #4 | Not listed |
| LMArena visionLMArena, Oct 19, 2026 | #12 | Not listed |
| LMArena Agent ArenaLMArena, Oct 19, 2026 | #15 | Not listed |
| Humanity's Last ExamScale AI | #8 | #15 |
| SWE-Bench ProScale AI, Sep 22, 2026 | #12 | #9 |
| Remote Labor IndexScale AI | #7 | Not listed |
| Vals IndexVals AI, Oct 19, 2026 | #13 | #9 |
| Terminal-Bench 4.0Vals AI, Oct 19, 2026 | Not listed | #12 |
| GPQA Diamond (run by Vals AI, archived)Vals AI, Sep 1, 2026 | #4 | Not listed |
| MMMU Pro (run by Vals AI, archived)Vals AI, Sep 1, 2026 | #4 | Not listed |
| CUA-bench (games)Vals AI, Oct 13, 2026 | #9 | Not listed |
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