Hardware · Memory

How much memory does a model need?

Pick an LLM and a context length. We add up the weights at every quantization, the KV cache that grows with context, and runtime overhead, then show the smallest systems and devices that hold it.

GLM-4.6 (355B-A32B) at 8K context

Quantization Weights KV cache + overhead Total Smallest hardware that holds it
Q2_K Low 143 GB 3.7 GB 146 GB 22 in all
Q3_K_M Low 175 GB 3.7 GB 179 GB 12 in all
Q4_K_M Good 218 GB 3.7 GB 221 GB 9 in all
Q5_K_M High 253 GB 3.7 GB 257 GB 7 in all
Q6_K High 293 GB 3.7 GB 296 GB 6 in all
Q8_0 Very high 378 GB 3.7 GB 382 GB 4 in all
F16 Full 714 GB 3.7 GB 717 GB Nothing in the catalog holds this on one machine.

Hardware is listed when its usable memory is at least 8% above the total. Macs count roughly two-thirds to three-quarters of unified memory as usable. Each link opens the full “can it run” breakdown with speed.

The rule of thumb

1 · WeightsParameters × bytes eachA 70B model at 4 bits per weight is about 70 × 0.6 ≈ 42 GB. Lower quantization shrinks it and costs some quality.
2 · KV cacheGrows with contextEvery token you keep in context stores keys and values for each layer. Doubling context doubles this part, so long documents cost real memory.
3 · OverheadLeave headroomThe runtime, the operating system and other apps need memory too. Aim for a total at least 10% under the memory your GPU or device can give a model.

Estimates come from published hardware specs and our open formulas, not from running the model on your machine. Real speed varies with runtime, drivers and settings. Numbers marked “Measured” come from a linked benchmark.

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