Is unified memory on MacBook Pro M4 Pro 48GB as fast as VRAM for Gemma 4 31B?

Not always. MacBook Pro M4 Pro 48GB can often fit larger models thanks to unified memory, but a discrete GPU with dedicated high-bandwidth VRAM may still decode faster once the model fits. For this combination, the important distinction is capacity versus sustained throughput.

Can Gemma 4 31B run on MacBook Pro M4 Pro 48GB?

Q: What should I upgrade first if Gemma 4 31B feels slow on MacBook Pro M4 Pro 48GB?

Remove offload with more accelerator memory. Prioritize a GPU or unified-memory tier that fits the whole model natively. Removing offload usually helps more than small compute gains.

BARELY — Tight on Memory

A73Great

Estimated — low-sample bucket· few comparable runs

Gemma 4 31B needs ~39.5 GB VRAM. MacBook Pro M4 Pro 48GB has 34.6 GB. With Q4_K_M quantization, expect ~7 tok/s.

Runtime: llama.cppCapacity: OffloadBandwidth: LowStack: StandardBottleneck: Host offload

Operating mode

Choose the run profile you care about

Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.

Current mode

Balanced

Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.

Capabilities:

Select quantization to explore

Q4_K_M (Medium quality) — 39.5 GB, 13.0 tok/s, Very compromised (needs ~2.3 GB host RAM)

39.5 GB required34.6 GB available

114% VRAM needed

4.9 GB over capacity — needs offload or smaller quantization

Fit status

Very compromised (needs ~2.3 GB host RAM)

Decode

13.0 tok/s

TTFT

14837 ms

Safe context

11K

Memory

39.5 GB / 34.6 GB

Offload

10%

Memory breakdown

Weights18.7 GB

KV Cache14.6 GB

Runtime0.9 GB

Headroom5.2 GB

See how fast it feels

See how fast it feelsGemma 4 31B on MacBook Pro M4 Pro 48GB
1st promptCold start — includes initialization
>Write a Python function to sort a list
Here's a Python function that sorts a list using quicksort:

def quicksort(arr):
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left   = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right  = [x for x in arr if x > pivot]
    return quicksort(left) + middle + quicksort(right)

# Example usage
numbers = [3, 6, 8, 10, 1, 2, 1]
print(quicksort(numbers))  # [1, 1, 2, 3, 6, 8, 10]

The algorithm picks a pivot, partitions the list into smaller, equal, and larger elements, then recursively sorts each partition and concatenates the results.
2nd promptWarm — model ready, no init overhead
>Now add type hints and a docstring
def quicksort(arr: list[int]) -> list[int]:
    """Sort a list using the quicksort algorithm.

    Args:
        arr: List of integers to sort.

    Returns:
        A new sorted list.
    """
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left   = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right  = [x for x in arr if x > pivot]
    return quicksort(left) + middle + quicksort(right)

Added type hints for the input and return type, plus a Google-style docstring.
Estimated: 13.0 tok/s decode · 14.8s TTFT (warm) · 33 tok/s prefill

What limits this setup

It fits through host-memory offload, and offload is the main reason performance drops.

CPU or host-memory offload is active

About 10% of the working set spills out of accelerator memory, which usually hurts latency and sustained decode throughput.

Very little memory headroom

You can run the model, but there is not much room left for longer context, bigger batches, extra apps, or future model updates.

Shared-memory contention still exists

The OS, browser, and inference runtime all compete for the same physical memory pool, so real-world headroom is less forgiving than raw capacity suggests.

Best improvement path

Remove offload with more accelerator memory

Prioritize a GPU or unified-memory tier that fits the whole model natively. Removing offload usually helps more than small compute gains.

Buy headroom, not only minimum fit

A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.

Increase host RAM if you keep offloading

This setup may need roughly {ram} GB of extra host RAM just for the offloaded portion, before OS and other tools.

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	A	Tight fit	8.5 tok/s	12413 ms	11K
Coding	A	Very compromised	6.9 tok/s	28043 ms	11K
Agentic Coding	F	Too heavy	4.7 tok/s	59415 ms	11K
Reasoning	A	Very compromised	6.9 tok/s	33141 ms	11K
RAG	F	Too heavy	4.7 tok/s	74269 ms	11K

Quantization options

How Gemma 4 31B (30.700000762939453B params) fits at each quantization level on MacBook Pro M4 Pro 48GB (34.6 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	12.0 GB	Low	A83
Q3_K_S	3	15.0 GB	Low	A85
NVFP4	4

Get started

Copy-paste commands to run Gemma 4 31B on your machine.

Run

ollama run gemma4:31b

Your hardware

More models your MacBook Pro M4 Pro 48GB can run

Model	Params	Grade	Decode	Capabilities
Qwen 3.6 35B A3B	35B	S	29.4 tok/s

Frequently asked questions

Can MacBook Pro M4 Pro 48GB run Gemma 4 31B?

Yes, MacBook Pro M4 Pro 48GB can run Gemma 4 31B with a A grade (Very compromised). Expected decode speed: 6.9 tok/s.

How much VRAM does Gemma 4 31B need?

Gemma 4 31B (30.700000762939453B parameters) requires approximately 39.5 GB of memory with Q4_K_M quantization.

What is the best quantization for Gemma 4 31B?

The recommended quantization for Gemma 4 31B is Q4_K_M, which balances quality and memory efficiency.

What speed will Gemma 4 31B run at on MacBook Pro M4 Pro 48GB?

On MacBook Pro M4 Pro 48GB, Gemma 4 31B achieves approximately 6.9 tokens per second decode speed with a time-to-first-token of 28043ms using Q4_K_M quantization.

Can MacBook Pro M4 Pro 48GB run Gemma 4 31B for coding?

For coding workloads, Gemma 4 31B on MacBook Pro M4 Pro 48GB receives a A grade with 6.9 tok/s and 11K context.

What context window can Gemma 4 31B use on MacBook Pro M4 Pro 48GB?

On MacBook Pro M4 Pro 48GB, Gemma 4 31B can safely use up to 11K tokens of context. The model's official context limit is 256K, but available memory constrains the safe maximum.

What should I upgrade first if Gemma 4 31B feels slow on MacBook Pro M4 Pro 48GB?

See all results for MacBook Pro M4 Pro 48GB See all hardware for Gemma 4 31B

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