Qwen2.5-72B-Instruct VRAM requirements
Qwen2.5-72B-Instruct needs about 45 GiB of GPU memory at Q4_K_M with an 8K context. That is tight on 48 GB cards like the L40S; 80 GB cards like the A100 have room for it. At 32K context it needs about 53 GiB, which fits 80 GB cards.
These are estimates from the model's config and file sizes, not measurements. How we calculate
VRAM by quantization
| Quant | File size | Total at 8K | Total at 32K |
|---|---|---|---|
| BF16 safetensors | 145.4 GB | 138.6 GiB–140.5 GiB | 146.1 GiB–148.2 GiB |
| GGUF Q8_0 (Qwen) | 77.5 GB | 74.8 GiB–76.8 GiB | 82.3 GiB–84.8 GiB |
| GGUF Q6_K (Qwen) | 59.9 GB | 58.4 GiB–60.0 GiB | 65.9 GiB–68.1 GiB |
| GGUF Q5_K_M (Qwen) | 51.7 GB | 50.8 GiB–52.3 GiB | 58.3 GiB–60.3 GiB |
| GGUF Q4_K_M | 44.0 GB | 43.6 GiB–45.0 GiB | 51.1 GiB–53.0 GiB |
Names like Q4_K_M and Q8_0 are quantization levels: fewer bits per weight means a smaller file and a small loss of quality. Totals add the KV cache (memory that grows with context length) and runtime buffers, for one chat at a time. Download files
Which GPUs can run it
| Memory | Usable | Examples | At 8K | At 32K |
|---|---|---|---|---|
| 8 GB | 7.0 GiB | RTX 4060, RTX 3060, RTX 5060 Ti +1 more | Does not fit | Does not fit |
| 10 GB | 9.0 GiB | RTX 3080 | Does not fit | Does not fit |
| 12 GB | 11.0 GiB | RTX 4070, RTX 3060, RTX 5070 +2 more | Does not fit | Does not fit |
| 16 GB | 14.0 GiB | RTX 4080 SUPER, RTX 5080, RX 7800 XT +5 more | Does not fit | Does not fit |
| 16 GB | 15.0 GiB | RTX 4060 Ti, RTX 4070 Ti SUPER | Does not fit | Does not fit |
| 20 GB | 18.0 GiB | RX 7900 XT | Does not fit | Does not fit |
| 24 GB | 22.0 GiB | RTX 4090, RX 7900 XTX, RTX 3090 | Does not fit | Does not fit |
| 32 GB | 30.0 GiB | RTX 5090 | Does not fit | Does not fit |
| 48 GB | 46.0 GiB | L40S | Tight fit | Does not fit |
| 80 GB | 78.0 GiB | A100, H100 | Runs comfortably | Runs comfortably |
| 64 GB · unified | 54.0 GiB | Apple M2 Max | Fits | Tight fit |
| 128 GB · unified | 96.0 GiB | Ryzen AI Max+ 395 | Runs comfortably | Runs comfortably |
| 128 GB · unified | 112.0 GiB | DGX Spark (GB10) | Runs comfortably | Runs comfortably |
| 128 GB · unified | 116.0 GiB | Apple M4 Max | Runs comfortably | Runs comfortably |
GGUF Q4_K_M, one chat at a time. Usable memory is the total minus a default reserve for the OS and display.
Detailed checks
Architecture
- PublisherQwen
- Hugging Face
Qwen/Qwen2.5-72B-Instruct - Total parameters72,706,203,648
- Layers80
- Query heads64
- KV heads8 (gqa)
- Head dimension128
- Context window32,768
The KV cache grows with context: about 2.5 GiB at 8K and 10 GiB at 32K in FP16. The model has 8 KV heads for 64 query heads (grouped-query attention), which keeps that cache small.
FAQ
Is the download size the same as VRAM use?
No. The Q4_K_M file is about 41 GiB, but with an 8K context the total is about 45 GiB, because the KV cache and runtime buffers sit on top of the weights.
How much memory does a longer context add?
For Qwen2.5-72B-Instruct the KV cache is about 2.5 GiB at 8K tokens and 10 GiB at 32K in FP16. The weights stay the same size.
Which quantization should I use?
Start with Q4_K_M (about 45 GiB at 8K). If you have the memory, BF16 needs about 140.5 GiB and stays closer to the original weights.
Download files
| Quant | Files | File size | Engine |
|---|---|---|---|
| BF16 safetensors | 145.41 GB 145,412,407,296 bytes | vllm, sglang | |
| GGUF Q8_0 (Qwen) | 77.53 GB 77,530,000,800 bytes | llama.cpp, ollama | |
| GGUF Q6_K (Qwen) | 59.86 GB 59,861,035,808 bytes | llama.cpp, ollama | |
| GGUF Q5_K_M (Qwen) | 51.67 GB 51,673,983,488 bytes | llama.cpp, ollama | |
| GGUF Q4_K_M | 44.01 GB 44,010,465,472 bytes | llama.cpp, ollama |
How this number is calculated
Total = weight file + KV cache + runtime buffers. The range spans low to high runtime overhead for the engine shown.
GGUF Q4_K_M · 8,192 tokens · llama.cpp
- Weights (file)
- 40.99 GiB (44,010,465,472 bytes)
- KV cache
- 2.50 GiB (2,684,354,560 bytes)
- Runtime buffers
- 0.13 GiB–1.49 GiB
- Total
- 43.61 GiB–44.98 GiB
- Requested context is within the recorded native window of 32768 tokens.
- Full-resident weight estimates use total parameters, including inactive MoE experts.
- Weight bytes come from the selected weight files only, not from every file in the repository.
- Download file size is not peak GPU memory. Runtime layout, allocator padding, and KV are extra.
- Weight bytes come from 12 published safetensors shards totaling 44010465472 bytes.
- Context budget is the number of cached tokens per sequence (prompt plus reserved generation).
- Concurrent sequences share one model replica; weights are not multiplied by sequence count.
- KV dtype is independent of weight quantization unless you change it.
Related pages
Sources
- Qwen2.5-72B-Instruct model card
- config.json — revision 495f39366efef23836d0cfae4fbe635880d2be31
- safetensors index — metadata.total_size=145412407296
- Artifact repo Qwen/Qwen2.5-72B-Instruct-GGUF
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