Is unified memory on MacBook Air M3 24GB as fast as VRAM for InternLM 20B?

Not always. MacBook Air M3 24GB 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 InternLM 20B run on MacBook Air M3 24GB?

Q: What should I upgrade first if InternLM 20B feels slow on MacBook Air M3 24GB?

Move to a larger memory pool. A larger unified-memory SKU or a discrete high-bandwidth GPU is the cleanest way to make this model practical.

NO — Won't Fit

F0Won't run

Estimated from fit model

InternLM 20B needs ~36.2 GB but MacBook Air M3 24GB only has 17.3 GB. Try a smaller quantization or lighter model.

Runtime: llama.cppCapacity: No fitBandwidth: Very lowStack: StandardBottleneck: Memory capacity

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

Q5_K_M (High quality) — 36.2 GB, exceeds 17.3 GB available

36.2 GB required17.3 GB available

209% VRAM needed

18.9 GB over capacity — needs offload or smaller quantization

Fit status

Too heavy

Decode

2.2 tok/s

TTFT

89319 ms

Safe context

Memory

36.2 GB / 17.3 GB

Offload

50%

Memory breakdown

Weights14.4 GB

KV Cache18.3 GB

Runtime0.9 GB

Headroom2.6 GB

See how fast it feels

With memory offload — actual speed may be lower

See how fast it feelsInternLM 20B on MacBook Air M3 24GB
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: 2.2 tok/s decode · 89.3s TTFT (warm) · 5 tok/s prefill

What limits this setup

Usable shared or unified memory is the main blocker for this model.

Not enough usable memory

The model needs 36.2 GB, but this setup only exposes 17.3 GB of usable shared or unified memory.

Best improvement path

Move to a larger memory pool

A larger unified-memory SKU or a discrete high-bandwidth GPU is the cleanest way to make this model practical.

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	F	Too heavy	2.7 tok/s	39340 ms	4K
Coding	F	Too heavy	2.2 tok/s	89320 ms	4K
Agentic Coding	F	Too heavy	2.2 tok/s	129919 ms	4K
Reasoning	F	Too heavy	2.2 tok/s	105559 ms	4K
RAG	F	Too heavy	2.2 tok/s	162399 ms	4K

Quantization options

How InternLM 20B (20B params) fits at each quantization level on MacBook Air M3 24GB (17.3 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	7.8 GB	Low	B59
Q3_K_S	3	9.8 GB	Low	B59
NVFP4	4

Upgrade options

Hardware that runs InternLM 20B well

Mac mini M4 64GBBudget pick

64 GB Unified (+40)120 GB/s (+20)

Makes the model fit on the accelerator instead of staying completely out of reach.8 tok/s decode

Makes the model fit on the accelerator instead of staying completely out of reach.

Removes host-memory offload, which is usually the single biggest latency and throughput win.

~$1,099 MSRP

MacBook Pro M4 Pro 64GBBest value

64 GB Unified (+40)273 GB/s (+173)

Makes the model fit on the accelerator instead of staying completely out of reach.19.4 tok/s decode

Makes the model fit on the accelerator instead of staying completely out of reach.

Removes host-memory offload, which is usually the single biggest latency and throughput win.

~$1,599 MSRP

MacBook Pro M4 Max 96GBApple upgrade

96 GB Unified (+72)546 GB/s (+446)

Makes the model fit on the accelerator instead of staying completely out of reach.30.7 tok/s decode

Makes the model fit on the accelerator instead of staying completely out of reach.

Removes host-memory offload, which is usually the single biggest latency and throughput win.

~$2,499 MSRP

Frequently asked questions

Can MacBook Air M3 24GB run InternLM 20B?

No, InternLM 20B requires more memory than MacBook Air M3 24GB provides.

How much VRAM does InternLM 20B need?

InternLM 20B (20B parameters) requires approximately 36.2 GB of memory with Q5_K_M quantization.

What is the best quantization for InternLM 20B?

The recommended quantization for InternLM 20B is Q5_K_M, which balances quality and memory efficiency.

What speed will InternLM 20B run at on MacBook Air M3 24GB?

On MacBook Air M3 24GB, InternLM 20B achieves approximately 2.2 tokens per second decode speed with a time-to-first-token of 89320ms using Q5_K_M quantization.

Can MacBook Air M3 24GB run InternLM 20B for coding?

For coding workloads, InternLM 20B on MacBook Air M3 24GB receives a F grade with 2.2 tok/s and 4K context.

What context window can InternLM 20B use on MacBook Air M3 24GB?

On MacBook Air M3 24GB, InternLM 20B can safely use up to 4K tokens of context. The model's official context limit is 8K, but available memory constrains the safe maximum.

What should I upgrade first if InternLM 20B feels slow on MacBook Air M3 24GB?

See all results for MacBook Air M3 24GB See all hardware for InternLM 20B

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