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
Every 70B build in the catalog
5 buildsDense 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.
| Model | Quant | Weights (GB) | At 8k (GB) | At 32k (GB) | Min RAM (GB) | Smallest GPU | Smallest Mac |
|---|---|---|---|---|---|---|---|
| Llama 3.3 70B Instruct70B params | Q4_K_M | 42 | 44.5 | 52 | 64 | RTX PRO 600096 GB · est. 36 tok/s | 64 GBM2 Ultra · est. 14 tok/s |
| Llama 3.3 70B Instruct (Q6)70B params | Q6_K | 57.9 | 60.4 | 67.9 | 96 | RTX PRO 600096 GB · est. 27 tok/s | 96 GBM2 Ultra · est. 10 tok/s |
| Llama 3.3 70B Instruct (Q8)70B params | Q8_0 | 75 | 77.5 | 85 | 96 | RTX PRO 600096 GB · est. 21 tok/s | 96 GBM2 Ultra · est. 8 tok/s |
| Llama 3.1 70B Instruct70B params | Q4_K_M | 42 | 44.5 | 52 | 64 | RTX PRO 600096 GB · est. 36 tok/s | 64 GBM2 Ultra · est. 14 tok/s |
| DeepSeek-R1 Distill Llama 70B70B params | Q4_K_M | 42 | 44.5 | 52 | 64 | RTX PRO 600096 GB · est. 36 tok/s | 64 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.
Ways to run Llama 3.3 70B Instruct at Q4_K_M
7 setupsThe 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.
| Setup | Memory | Fit | Verdict | Speed | Max context |
|---|---|---|---|---|---|
| RTX 4090 | 24 GB VRAM | With offload | No | est. 2 tok/srough estimate, offload not measured | n/a |
| RTX 5090 | 32 GB VRAM | With offload | Tight | est. 7 tok/srough estimate, offload not measured | n/a |
| 2 x RTX 4090pooled fit only, no speed estimate | 48 GB pooled VRAM | Fits, pooled | n/a | n/a | under 8k |
| 48 GB MacM5 Max profile | 48 GB unified memory | Over budget | Tight | est. 9 tok/stypical error 10% | n/a |
| 64 GB MacM2 Ultra profile | 64 GB unified memory | Fits fully | Runs well | est. 14 tok/stypical error 10% | 16k |
| RTX PRO 6000 | 96 GB VRAM | Fits fully | Runs well | est. 36 tok/stypical error 10% | 128k |
| Ryzen AI Max+ 395 | 110 GB unified memory | Fits fully | Tight | est. 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.
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%).
Go deeper
VRAM per model size (1B to 80B) · best hardware for Llama 3.3 70B Instruct · best LLM for 24GB VRAM · VRAM calculator · LLM memory calculator
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