Is unified memory on Mac Studio M3 Ultra 256GB as fast as VRAM for CodeLlama 13B Instruct?

Not always. Mac Studio M3 Ultra 256GB 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 CodeLlama 13B Instruct run on Mac Studio M3 Ultra 256GB?

YES — Runs Great

A72Great

Estimated from fit model

CodeLlama 13B Instruct needs ~48.7 GB VRAM. Mac Studio M3 Ultra 256GB has 184.3 GB. With Q4_K_M quantization, expect ~70 tok/s.

Runtime: llama.cppCapacity: RoomyBandwidth: HighStack: StandardBottleneck: Balanced

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) — 48.7 GB, 70.2 tok/s, Runs well

48.7 GB required184.3 GB available

26% VRAM used

Fit status

Runs well

Decode

70.2 tok/s

TTFT

2757 ms

Safe context

16K

Memory

48.7 GB / 184.3 GB

Memory breakdown

Weights7.9 GB

KV Cache12.2 GB

Runtime0.9 GB

Headroom27.6 GB

See how fast it feels

See how fast it feelsCodeLlama 13B Instruct on Mac Studio M3 Ultra 256GB
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: 70.2 tok/s decode · 2.8s TTFT (warm) · 176 tok/s prefill

What limits this setup

This setup is broadly balanced for this model.

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

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	A	Runs well	70.2 tok/s	1504 ms	16K
Coding	A	Runs well	70.2 tok/s	2757 ms	16K
Agentic Coding	A	Runs well	70.2 tok/s	4010 ms	16K
Reasoning	A	Runs well	70.2 tok/s	3258 ms	16K
RAG	A	Runs well	70.2 tok/s	5012 ms	16K

Quantization options

How CodeLlama 13B Instruct (13B params) fits at each quantization level on Mac Studio M3 Ultra 256GB (184.3 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	5.1 GB	Low	B62
Q3_K_S	3	6.4 GB	Low	B62
NVFP4	4

Get started

Copy-paste commands to run CodeLlama 13B Instruct on your machine.

Run

lms load CodeLlama-13b-Instruct-hf && lms server start

Your hardware

More models your Mac Studio M3 Ultra 256GB can run

Model	Params	Grade	Decode	Capabilities
Devstral 2 123B Instruct	123B	S	8.1 tok/s
Qwen3-Coder 30B A3B Instruct	30.5B	S

Frequently asked questions

Can Mac Studio M3 Ultra 256GB run CodeLlama 13B Instruct?

Yes, Mac Studio M3 Ultra 256GB can run CodeLlama 13B Instruct with a A grade (Runs well). Expected decode speed: 70.2 tok/s.

How much VRAM does CodeLlama 13B Instruct need?

CodeLlama 13B Instruct (13B parameters) requires approximately 48.7 GB of memory with Q4_K_M quantization.

What is the best quantization for CodeLlama 13B Instruct?

The recommended quantization for CodeLlama 13B Instruct is Q4_K_M, which balances quality and memory efficiency.

What speed will CodeLlama 13B Instruct run at on Mac Studio M3 Ultra 256GB?

On Mac Studio M3 Ultra 256GB, CodeLlama 13B Instruct achieves approximately 70.2 tokens per second decode speed with a time-to-first-token of 2757ms using Q4_K_M quantization.

Can Mac Studio M3 Ultra 256GB run CodeLlama 13B Instruct for coding?

For coding workloads, CodeLlama 13B Instruct on Mac Studio M3 Ultra 256GB receives a A grade with 70.2 tok/s and 16K context.

What context window can CodeLlama 13B Instruct use on Mac Studio M3 Ultra 256GB?

On Mac Studio M3 Ultra 256GB, CodeLlama 13B Instruct can safely use up to 16K tokens of context. The model's official context limit is 16K, but available memory constrains the safe maximum.

See all results for Mac Studio M3 Ultra 256GB See all hardware for CodeLlama 13B Instruct

Embed this result▼

Paste this snippet into any page to show a live fit card.

<iframe src="https://willitrunai.com/embed/codellama-13b-instruct-on-m3-ultra-256gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>

Preview: