How much memory does Gemma 4 31B need at Q4?

The Q4 figure used here is 19.7 GB. GGUF file size plus an FP16 KV-cache estimate at 8,192 tokens. The cache counts only the layers and heads named in the method on the About page.

What is the cheapest catalog device that runs Gemma 4 31B at Q4?

Radeon RX 7900 XTX, list price $999.

How fast is Gemma 4 31B on the Mac mini M4 16GB, as a bandwidth estimate?

About 6.55 tok/s at Q4. That is device bandwidth divided by active weight bytes, not a measured run.

No. Gemma 4 31B does not fit on the Mac mini M4 16GB at Q4. The estimate is 19.7 GB and usable memory is 11.2 GB.

Can the Mac mini M4 16GB run Gemma 4 31B?

Data updated 16 October 2026. Last reviewed the same day, when this catalog snapshot was written.

Usable memory on this 16 GB unified-memory config is 11.2 GB (70% of the sticker figure). A result under 2 GB of headroom is labeled tight.

Quant ladder

Estimated memory for Gemma 4 31B on Mac mini M4 16GB
Quant	Estimate	Headroom	Est. tok/s	Verdict
Q4	19.7 GB	-8.5 GB	6.55 tok/s	No
Q8	34.0 GB	-22.8 GB	3.68 tok/s	No
FP16	75.1 GB	-63.9 GB	1.92 tok/s	No

GGUF file size plus an FP16 KV-cache estimate at 8,192 tokens. The cache counts only the layers and heads named in the method on the About page.
Formula estimate: parameter count × bytes per weight × 1.20. No GGUF file size is stored for this quant.
Tokens/sec is a bandwidth roofline: GB/s divided by active weight GB. It is not a measured generation speed.

KV cache at 8K and 32K

FP16 KV-cache estimate: 1.3 GB at 8,192 tokens and 5.4 GB at 32,768 tokens. GQA counts two tensors (K and V) for the stored KV heads and head dimension. config.json also sets a sliding window of 1,024 tokens. The figures above assume every counted layer stores the full context, so they can overstate cache on sliding layers.

Offload

The Q4 estimate is 8.5 GB over usable unified memory. There is no separate GPU to spill from.

Ollama

This command pulls the Q4_K_M file from unsloth/gemma-4-31B-it-GGUF, the Hub repo whose file size is used above. It is not an official Ollama library tag.

ollama run hf.co/unsloth/gemma-4-31B-it-GGUF:Q4_K_M

What fits instead

Cheapest catalog device at Q4: Radeon RX 7900 XTX
Closest catalog model that still fits at Q4: Qwen2.5 14B Instruct.

All hardware for Gemma 4 31B · All models for the Mac mini M4 16GB

Questions

How much memory does Gemma 4 31B need at Q4?: The Q4 figure used here is 19.7 GB. GGUF file size plus an FP16 KV-cache estimate at 8,192 tokens. The cache counts only the layers and heads named in the method on the About page.
Can the Mac mini M4 16GB run Gemma 4 31B?: No. Gemma 4 31B does not fit on the Mac mini M4 16GB at Q4. The estimate is 19.7 GB and usable memory is 11.2 GB.
What is the cheapest catalog device that runs Gemma 4 31B at Q4?: Radeon RX 7900 XTX, list price $999.
How fast is Gemma 4 31B on the Mac mini M4 16GB, as a bandwidth estimate?: About 6.55 tok/s at Q4. That is device bandwidth divided by active weight bytes, not a measured run.