How much memory does Qwen3.5 4B need?

About 2.3 GB of weights at 4-bit, plus room for the context: 3.8 GB in all. On a Mac that means 8 GB of unified memory or more, since macOS lets the GPU use about 75% of it by default.

How fast is Qwen3.5 4B on a Mac?

Writing speed depends on memory bandwidth. The fastest Mac for it here is an M5 Ultra with 96 GB at about 126–223 tokens a second (8-bit). The smallest Mac that runs it, with 8 GB, manages about 10–19 on an M3.

Does quantization hurt Qwen3.5 4B?

At 4 bits most models stay close to the original quality; below 4 bits quality drops faster. Pick the highest precision that fits your Mac with room to spare.

Can a Mac run Qwen3.5 4B? RAM and speed

Memory at each precision

Version	Weights	With context	Smallest Mac
8-bit	4.3 GB	5.8 GB	8 GB
6-bit	3.3 GB	4.8 GB	8 GB
4-bit	2.3 GB	3.8 GB	8 GB
3-bit lower quality	1.8 GB	3.3 GB	8 GB
2-bit lower quality	1.3 GB	2.8 GB	8 GB

On every Apple chip

The smallest memory size of each chip that runs Qwen3.5 4B, the best version that fits it, and the writing speed you can expect.

Chip	Needs	Version	Tokens/s
M6	16 GB	8-bit Runs well	16–28
M5 Ultra	96 GB	8-bit Runs well	126–223
M5 Max	36 GB	8-bit Runs well	48–86
M5 Pro	24 GB	8-bit Runs well	32–57
M5	16 GB	8-bit Runs well	16–28
M4 Max	36 GB	8-bit Runs well	43–76
M4 Pro	24 GB	8-bit Runs well	29–51
M4	16 GB	8-bit Runs well	13–22
M3 Ultra	96 GB	8-bit Runs well	86–152
M3 Max	36 GB	8-bit Runs well	31–56
M3 Pro	18 GB	8-bit Runs well	16–28
M3	8 GB	8-bit Runs well	10–19
M2 Ultra	64 GB	8-bit Runs well	84–149
M2 Max	32 GB	8-bit Runs well	42–74
M2 Pro	16 GB	8-bit Runs well	21–37
M2	8 GB	8-bit Runs well	10–19
M1 Ultra	64 GB	8-bit Runs well	84–149
M1 Max	32 GB	8-bit Runs well	42–74
M1 Pro	16 GB	8-bit Runs well	21–37
M1	8 GB	4-bit Runs well	13–24

How to run it

The easy way: download MLX Harness, free and open source. Search for Qwen3.5 4B, 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/Qwen3.5-4B-MLX-4bitBuild: mlx-community/Qwen3.5-4B-MLX-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 4B

Made by	Qwen (Alibaba)
Parameters	4B (dense)
Context	256K tokens
Licence	Apache-2.0
Released	2026-02
Input	Text and images
Weights	Qwen/Qwen3.5-4B

Questions

How much memory does Qwen3.5 4B need?: About 2.3 GB of weights at 4-bit, plus room for the context: 3.8 GB in all. On a Mac that means 8 GB of unified memory or more, since macOS lets the GPU use about 75% of it by default.
How fast is Qwen3.5 4B on a Mac?: Writing speed depends on memory bandwidth. The fastest Mac for it here is an M5 Ultra with 96 GB at about 126–223 tokens a second (8-bit). The smallest Mac that runs it, with 8 GB, manages about 10–19 on an M3.
Does quantization hurt Qwen3.5 4B?: At 4 bits most models stay close to the original quality; below 4 bits quality drops faster. Pick the highest precision that fits your Mac with room to spare.

For your model card or README

Shows the smallest Mac that runs Qwen3.5 4B well and links here.

[![Runs on a Mac](https://mlx.app/badge/run/qwen3.5-4b.svg)](https://mlx.app/run/qwen3.5-4b)

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.