In short
How they differ.
Worked out from the figures below. Prices and specs are the makers' own, read Oct 20, 2026.
- Kimi K3 reads more at once: a context window of 1M tokens against 128K.
- Both can be downloaded and run on your own machine.
- No independent board we follow ranks both models yet.
Side by side
The specs.
| gpt-oss-120b | Kimi K3 | |
|---|---|---|
| Made by | OpenAI · US | Moonshot AI · China |
| Released | Aug 5, 2025 | Not stated |
| Price per 1M tokens | Free to download; hosts set prices | $3 in / $15 out |
| Context window | 128K | 1M |
| Takes in | text | text, image, video |
| Download and run it yourself | Yes (Apache 2.0) | Yes (Kimi K3 License) |
| Size | 117B parameters, 5.1B active | 2.8T parameters, 104B active |
| Maker says | “production, general purpose, high reasoning use cases” | “Kimi K3 is an open-weight, native multimodal agentic model and our most capable model to date.” |
| 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 | gpt-oss-120b | Kimi K3 |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | Not listed | #17157.42 |
| LMArena textLMArena, Oct 15, 2026 | Not listed | #18 |
| LMArena coding chatsLMArena, Oct 15, 2026 | Not listed | #12 |
| LMArena WebDevLMArena, Oct 19, 2026 | Not listed | #16 |
| LMArena mathLMArena, Oct 15, 2026 | Not listed | #16 |
| Humanity's Last ExamScale AI | Not listed | #14 |
| SWE-Bench ProScale AI, Sep 22, 2026 | Not listed | #4 |
| Vals IndexVals AI, Oct 19, 2026 | Not listed | #18 |
| Vibe Code BenchVals AI, Oct 18, 2026 | Not listed | #16 |
| ProofBenchVals AI, Oct 12, 2026 | Not listed | #12 |
| GPQA Diamond (run by Vals AI, archived)Vals AI, Sep 1, 2026 | Not listed | #12 |
| MMMU Pro (run by Vals AI, archived)Vals AI, Sep 1, 2026 | Not listed | #11 |
| Vectara hallucination testVectara, Oct 16, 2026 | #9214.2% | Not listed |
More comparisons