# Can I run gpt-oss 120B on Apple M3 Ultra (256GB)?

> **Yes, it runs.** Runs at Q4_K_M using ~62.4 GB of ~192 GB usable. You have room for Q8_0 for higher quality.

Last validated: 2026-06-15.

## Memory math
- gpt-oss 120B: 117B (MoE, 5.1B active); Q4_K_M weighs 59.03 GB on disk.
- At Q4_K_M with a 4k context it needs ~62.4 GB (weights + KV cache + ~0.8 GB runtime overhead, ±15% with context length).
- Apple M3 Ultra (256GB): 256 GB unified, ~192 GB usable for model weights.
- Headroom: ~129.6 GB; it also fits Q8_0 for higher quality.

## How to run
Recommended quant: Q4_K_M. Best tool on macOS: LM Studio.

```sh
ollama run gpt-oss:120b
```

## Run gpt-oss 120B on other devices
- [Apple M4 Max (128GB)](https://localmodel.run/can-i-run/gpt-oss-120b/apple-m4-max-128gb)
- [Apple M5 Max (128GB)](https://localmodel.run/can-i-run/gpt-oss-120b/apple-m5-max-128gb)

## Other models that run on Apple M3 Ultra (256GB)
- [Qwen3 235B A22B (235B)](https://localmodel.run/can-i-run/qwen3-235b-a22b/apple-m3-ultra-256gb)
- [Llama 4 Scout (109B)](https://localmodel.run/can-i-run/llama-4-scout/apple-m3-ultra-256gb)
- [Sarvam-105B (105B)](https://localmodel.run/can-i-run/sarvam-105b/apple-m3-ultra-256gb)
- [Qwen2.5 72B (72B)](https://localmodel.run/can-i-run/qwen2.5-72b/apple-m3-ultra-256gb)
- [Llama 3.3 70B (70B)](https://localmodel.run/can-i-run/llama-3.3-70b/apple-m3-ultra-256gb)
- [Mixtral 8x7B (46.7B)](https://localmodel.run/can-i-run/mixtral-8x7b/apple-m3-ultra-256gb)

Estimate, not a guarantee. Sources: https://ollama.com/library/gpt-oss, https://ollama.com/library/gpt-oss/tags, https://huggingface.co/ggml-org/gpt-oss-120b-GGUF, https://huggingface.co/openai/gpt-oss-120b.
More: https://localmodel.run/can-i-run/gpt-oss-120b/apple-m3-ultra-256gb