robotnurse./gear/how-much-ram-for-local-llms — buyers' notes
How much RAM do you need for 7B, 13B, and 30B models?
Roughly: 7B models want about 8GB, 13B about 16GB, and 30B about 32GB of unified memory at q4, each with room for context — q8 roughly doubles each figure. 96GB+ buys comfort and headroom rather than capability you'll use every day.
Unified-memory budgets for 7B/13B/30B open-weight models at q4–q8: what fits in 32GB, 64GB, and why 96GB+ buys comfort, not just headroom.
At q4, a 7B model wants ~4–5GB of weights plus context; 13B ~8–10GB; 30B ~18–20GB. Leave headroom.
Unified memory is shared between the model and your workflow. Buy the step above what your model needs; the comfort costs far less than a second machine.
RELATED NOTES the full memory guide: RAM vs VRAM, context costs, offload math → · Mac Studio vs GPU PC — which box earns the desk → · three working builds under $3,000 →
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