Updated 2026-10-31

VRAM for a 70B Model

Short answer: A 70B model like Llama 3.3 70B Instruct needs about 42 GB at Q4_K_M, 57.9 GB at Q6_K or 75 GB at Q8_0, plus an estimated 10 GB of KV cache at 32k context. The smallest single GPU that runs the Q4_K_M build is the 96 GB RTX PRO 6000, at est. 36 tok/s (typical error 10%); a Mac needs 64 GB (ModelFit, updated 2026-10-31).

Q4_K_M weights
42 GB
KV cache at 32k
~10 GB
Smallest single GPU
96 GBRTX PRO 6000
Smallest Mac
64 GB
Table 1By build

Every 70B build in the catalog

5 builds

Dense 70B-class models in the ModelFit catalog, one row per quantized build. Totals add the KV cache at 8k and 32k of context to the weights.

ModelQuantWeights (GB)At 8k (GB)At 32k (GB)Min RAM (GB)Smallest GPUSmallest Mac
Llama 3.3 70B Instruct70B paramsQ4_K_M4244.55264RTX PRO 600096 GB · est. 36 tok/s64 GBM2 Ultra · est. 14 tok/s
Llama 3.3 70B Instruct (Q6)70B paramsQ6_K57.960.467.996RTX PRO 600096 GB · est. 27 tok/s96 GBM2 Ultra · est. 10 tok/s
Llama 3.3 70B Instruct (Q8)70B paramsQ8_07577.58596RTX PRO 600096 GB · est. 21 tok/s96 GBM2 Ultra · est. 8 tok/s
Llama 3.1 70B Instruct70B paramsQ4_K_M4244.55264RTX PRO 600096 GB · est. 36 tok/s64 GBM2 Ultra · est. 14 tok/s
DeepSeek-R1 Distill Llama 70B70B paramsQ4_K_M4244.55264RTX PRO 600096 GB · est. 36 tok/s64 GBM2 Ultra · est. 14 tok/s

KV cache: 2.5 GB at 8k and 10 GB at 32k per model, a size-class estimate (no exact per-token figure in the catalog). Speeds are ModelFit estimates, not measured runs. Updated 2026-10-31.

Table 2By setup

Ways to run Llama 3.3 70B Instruct at Q4_K_M

7 setups

The engine's verdict for the 42 GB build on each memory size, smallest first, with the longest context (8k to 128k) that still fits next to the weights.

SetupMemoryFitVerdictSpeedMax context
RTX 409024 GB VRAMWith offloadNoest. 2 tok/srough estimate, offload not measuredn/a
RTX 509032 GB VRAMWith offloadTightest. 7 tok/srough estimate, offload not measuredn/a
2 x RTX 4090pooled fit only, no speed estimate48 GB pooled VRAMFits, pooledn/an/aunder 8k
48 GB MacM5 Max profile48 GB unified memoryOver budgetTightest. 9 tok/stypical error 10%n/a
64 GB MacM2 Ultra profile64 GB unified memoryFits fullyRuns wellest. 14 tok/stypical error 10%16k
RTX PRO 600096 GB VRAMFits fullyRuns wellest. 36 tok/stypical error 10%128k
Ryzen AI Max+ 395110 GB unified memoryFits fullyTightest. 5 tok/stypical error 10%128k

Verdicts and speeds come from the same engine as each GPU page and the calculator. A pooled rig is a fit check only (the rig calculator rule: 90% of the combined VRAM); split speed depends on the cards and the link between them, so none is estimated. A Mac row uses the engine's machine for that memory size.

How these numbers are made

  • Sizes: the loaded size and minimum memory of each build from the open dataset (/api/dataset/, CC BY 4.0). Parameter count from the publisher's model card (Llama 3.3 70B Instruct).
  • Context: KV-cache figures assume an fp16 cache, the llama.cpp/Ollama default. Standard GQA models use a size-class estimate (8 KV heads x 128 head dim class); hybrid linear-attention models (Qwen3.5/3.6, Qwen3-Next) use the exact per-token cost from their published config, since only their sparse full-attention layers cache KV. A q8_0 KV cache roughly halves either figure. Estimates, not measurements.
  • Fit: 90% of a card's VRAM, 70% to 85% of a Mac's unified memory, then the engine's verdict, as in the calculator.
  • Speed: decode tokens per second at 4k of context from the fitted bandwidth model, each with its typical error (the median gap to measured runs on hardware the model was not fitted on). A row with CPU offload has no measured band. How the estimates work.
FAQ

Frequently asked questions

Can a 24 GB GPU run a 70B model?

Not on its own. Llama 3.3 70B Instruct at Q4_K_M needs 42 GB and a 24 GB card keeps about 22 GB for weights, so most of the model sits in system RAM: the engine rates the RTX 4090 "No" at est. 2 tok/s (rough estimate, offload not measured). Two of them pool 48 GB, about 43 GB for weights, which holds the weights with less than 8k of context left over.

How much RAM does a Mac need for a 70B model?

64 GB of unified memory is the smallest tier where the engine rates Llama 3.3 70B Instruct at Q4_K_M as running well, at est. 14 tok/s (typical error 10%) on the M2 Ultra it uses for that tier. The catalog's minimum for this build is 64 GB. macOS keeps part of unified memory for itself, so a Mac needs more total memory than the weights.

How much more memory does Q8_0 need than Q4_K_M?

Llama 3.3 70B Instruct grows from 42 GB at Q4_K_M to 75 GB at Q8_0 in the catalog, 1.8x the memory for the same context. The smallest single card that runs it is still the RTX PRO 6000, at est. 21 tok/s (typical error 10%).

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