Memory at each precision
| Version | Weights | With context | Smallest Mac |
|---|---|---|---|
| 8-bit | 422 GB | 456 GB | more than any Mac |
| 6-bit | 323 GB | 348 GB | 512 GB |
| 4-bit | 223 GB | 241 GB | 512 GB |
| 3-bit lower quality | 174 GB | 188 GB | 256 GB |
| 2-bit lower quality | 124 GB | 134 GB | 192 GB |
On every Apple chip
The smallest memory size of each chip that runs Qwen3.5 397B A17B, the best version that fits it, and the writing speed you can expect.
| Chip | Needs | Version | Tokens/s |
|---|---|---|---|
| M6 | no size fits | Too big | – |
| M5 Ultra | 512 GB | 6-bit Runs well | 39–70 |
| M5 Max | no size fits | Too big | – |
| M5 Pro | no size fits | Too big | – |
| M5 | no size fits | Too big | – |
| M4 Max | no size fits | Too big | – |
| M4 Pro | no size fits | Too big | – |
| M4 | no size fits | Too big | – |
| M3 Ultra | 512 GB | 6-bit Runs well | 27–47 |
| M3 Max | no size fits | Too big | – |
| M3 Pro | no size fits | Too big | – |
| M3 | no size fits | Too big | – |
| M2 Ultra | 192 GB | 2-bit Runs well | 68–121 |
| M2 Max | no size fits | Too big | – |
| M2 Pro | no size fits | Too big | – |
| M2 | no size fits | Too big | – |
| M1 Ultra | no size fits | Too big | – |
| M1 Max | no size fits | Too big | – |
| M1 Pro | no size fits | Too big | – |
| M1 | no size fits | Too big | – |
How to run it
- The easy way: download MLX Harness, free and open source. Search for Qwen3.5 397B A17B, download the version that fits your Mac, and chat. It also serves the model to your other apps over an OpenAI-compatible API.Download MLX HarnessFree · Apple Silicon · macOS 14.5 or later
- In Terminal with Apple’s MLX:
pip install mlx-lmmlx_lm.chat --model mlx-community/Qwen3.5-397B-A17B-4bitBuild: mlx-community/Qwen3.5-397B-A17B-4bit on Hugging Face. Other precisions sit next to it.
Step by step: download and run LLMs on a Mac · how to use MLX Harness · MLX vs Ollama vs llama.cpp
About Qwen3.5 397B A17B
| Made by | Qwen (Alibaba) |
|---|---|
| Parameters | 397B total · 17B active (mixture of experts) |
| Context | 256K tokens |
| Licence | Apache-2.0 |
| Released | 2026-02 |
| Input | Text and images |
| Intelligence | 18.4 on the Artificial Analysis Intelligence Index |
| Weights | Qwen/Qwen3.5-397B-A17B |
Questions
- How much memory does Qwen3.5 397B A17B need?
- About 223 GB of weights at 4-bit, plus room for the context: 241 GB in all. On a Mac that means 512 GB of unified memory or more, since macOS lets the GPU use about 75% of it by default.
- How fast is Qwen3.5 397B A17B on a Mac?
- Writing speed depends on memory bandwidth. The fastest Mac for it here is an M5 Ultra with 512 GB at about 39–70 tokens a second (6-bit). The smallest Mac that runs it, with 512 GB, manages about 39–70 on an M5 Ultra.
- Why does Qwen3.5 397B A17B run faster than its size suggests?
- It is a mixture-of-experts model: it holds 397B parameters in memory but reads only 17B for each token, so it writes at the speed of a much smaller model.
Similar models
For your model card or README
Shows the smallest Mac that runs Qwen3.5 397B A17B well and links here.
[](https://mlx.app/run/qwen3.5-397b-a17b)How it’s worked out
Memory: the model’s parameters at 8, 6, 4, 3 or 2 bits per weight plus MLX’s group scales (half a bit per weight), or its native format, with room for the context on top. By default macOS lets the GPU use about 75% of unified memory. Speed: memory bandwidth divided by the bytes read per token is the ceiling for one conversation; in llama.cpp’s public Apple Silicon benchmarks real runs reach about 45% to 80% of it, which is the range shown. These are estimates, not measurements: measure your own Mac on MLX Bench. Model figures from each official model card, chip figures from Apple’s Tech Specs. Checked 2026-10-19. Same data as mlx.app/compare.