Can I Run Llama 4 on 48 GB system RAM?
Written by Jakub Rusinowski · Last updated April 5, 2025
Yes, but it is tight
Yes, but it is tight — Llama 4 Scout 17B at Q2_K needs about 38.2 GB of the 38.4 GB usable on 48 GB system RAM, leaving only ~0.2 GB before the runtime starts swapping. Expect ~10.3 tok/s (estimated), with room for about 8,192 tokens of context.
Confidence: medium · Recommended quantization: Q2_K · Estimated speed: ~10.3 tok/s
48 GB system RAM — what it gives a model
| Usable memory for models | 38.4 GB |
| Memory bandwidth | 90 GB/s |
Llama 4 on 48 GB system RAM: memory by quantization
| Quant | Memory needed | Fits 38.4 GB? | Max context | Est. speed | Download |
|---|
| F16 | 220.4 GB | ✗ No | — | — | 218 GB |
| Q8_0 | 118.2 GB | ✗ No | — | — | 115.8 GB |
| Q6_K | 91.8 GB | ✗ No | — | — | 89.4 GB |
| Q5_K_M | 79.7 GB | ✗ No | — | — | 77.3 GB |
| Q4_K_M | 68.2 GB | ✗ No | — | — | 65.8 GB |
| Q3_K_M | 48.9 GB | ✗ No | — | — | 46.5 GB |
| Q2_K | 38.2 GB | ✓ Yes | 8K | ~10.3 tok/s | 35.8 GB |
Which Llama 4 sizes fit
| Variant | Needs at Q4_K_M | Fits? | Est. speed |
|---|
| Llama 4 Maverick 17B | 243.9 GB | ✗ Too large | — |
| Llama 4 Scout 17B | 68.2 GB | ✗ Too large | — |
What to watch out for
- Only ~0.2 GB of headroom at Q2_K: a longer context or a second application can push this into swapping.
- Q2_K is the only quantization that fits, and it is a heavily degraded one — expect noticeably worse output than the same model at Q4_K_M. A smaller model at Q4 is usually the better trade.
- 2 larger variants of Llama 4 do not fit and would need CPU offload or different hardware.
- These figures assume CPU-only inference. Any discrete GPU, even an 8 GB one, will be several times faster for models that fit in its VRAM.
Recommended setup
llama.cpp (CPU build) or Ollama — both run without a GPU
How these numbers are calculated
- Memory need = quantized weights + KV cache at 8,192 tokens (f16) + 0.8 GB runtime overhead.
- 38.4 GB of the 48 GB is treated as usable for model weights (80% — the rest is the OS and running applications).
- DDR5-5600 dual channel at 89.6 GB/s peak. CPU decode is assumed to sustain 35% of that peak, because CPU inference is not purely bandwidth-bound — it also spends real time in compute and thread synchronisation. This figure is an assumption, not a fitted constant: no CPU measurement is in the calibration set.
- CPU-only inference: no GPU is assumed. A GPU of any size will beat these figures substantially.
- Throughput is a memory-bandwidth roofline estimate, not a measurement. It is labelled "estimated" everywhere it appears.
- KV cache is computed from this model's published attention configuration.
FAQ
Can I run Llama 4 on 48 GB system RAM?
Yes, but it is tight — Llama 4 Scout 17B at Q2_K needs about 38.2 GB of the 38.4 GB usable on 48 GB system RAM, leaving only ~0.2 GB before the runtime starts swapping. Expect ~10.3 tok/s (estimated), with room for about 8,192 tokens of context.
Which quantization of Llama 4 should I use on 48 GB system RAM?
Q2_K — it needs about 38.2 GB of the 38.4 GB available, downloads as roughly 35.8 GB, and runs at an estimated 10.3 tokens/sec with up to 8K of context.
What limits Llama 4 on 48 GB system RAM?
Nothing binding — the model fits with headroom and generates at a usable speed on this hardware.
Which runtime should I use?
llama.cpp (CPU build) or Ollama — both run without a GPU
Other RAM Capacities
Other Models on 48 GB system RAM
Llama 4 on GPUs
What This Model Is Good At
Model & Tools
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