The M4 for local AI.

The M4 has up to 32 GB of unified memory, read at up to 120 GB/s. Here's what that means for running language models on a Mac with it, worked out from Apple's own figures.

1The specs that matter for AI

Unified memory32 GB
Memory bandwidth120 GB/s
Found inMacBook Air (2025), 14-inch MacBook Pro (2024), Mac mini (2024), iMac (2024)
Dedicated seat for itCore seat: mines up to 20 MLX a day

2Which models fit

At 4 bits per weight a model needs a little over half a gigabyte per billion parameters, plus room for its context and macOS. With 32 GB, the M4 comfortably holds models up to about 42 billion parameters.

Model at 4-bitMemory it needsFits on the M4
8B model4.5 GBYes
14B model7.9 GBYes
32B model18 GBYes
70B model39.4 GBNo
gpt-oss-120b, mixture-of-experts65 GBNo
Qwen3.5-397B-A17B, mixture-of-experts223.3 GBNo
DeepSeek-V4.1-Flash, mixture-of-experts316 GBNo

3How fast it runs

Writing text is limited by memory bandwidth: every new token reads the model's active weights once. Dividing the M4's 120 GB/s by the bytes read per token gives the ceiling below. Real runs usually reach about 45% to 80% of it (llama.cpp benchmarks).

Model at 4-bitRead per tokenCeiling for one chat
8B model4.5 GB27 tokens/s
14B model7.9 GB15 tokens/s
32B model18 GB7 tokens/s

5Compare with other chips

6Questions

Can the M4 run a 70B model?
Not comfortably. A 70B model at 4-bit needs about 40 GB, and the M4 has at most 32 GB. Models up to about 42B parameters fit well.
How many tokens per second does the M4 get?
For an 8B model at 4-bit, the ceiling is about 27 tokens a second, and real runs reach roughly half to four fifths of it. Bigger models are proportionally slower.
Is the M4 good for AI?
For running models locally, memory and bandwidth matter most. The M4 has up to 32 GB at 120 GB/s, enough for models up to about 42 billion parameters. It can also earn by running AI work for MLX Network with MLX Node.

Sources

  1. Apple: Mac mini (2024) specssupport.apple.com
  2. llama.cpp: Apple Silicon benchmarksgithub.com
M4 for local LLMs: memory, speed and what fits | MLX