Free tools

GPU VRAM calculator

How much memory does that model actually need? Pick a model, quantization, and context length; see what fits, instantly and free.

44 GBmemory needed · Llama 4 70B at 4-bit, 16K context

Smallest single device that fits: L40S (48 GB)

RTX 4090 (24 GB)2x needed
RTX 5090 (32 GB)2x needed
L40S (48 GB)Fits
A100 (80 GB)Fits
H100 (80 GB)Fits
H200 (141 GB)Fits
B200 (192 GB)Fits
Mac M4 Max (128 GB unified)Fits
Mac M3 Ultra (512 GB unified)Fits

How it works

1
Pick the model
Named open-weight models or a generic size class. MoE models must fit their full weights, not just active parameters.
2
Set quantization and context
Weights shrink with quantization; the KV cache grows with context length. Both count.
3
Read the verdict
Every GPU that fits, the smallest that does, and what to do when nothing does.

Common questions

How is the VRAM requirement calculated?

Weights (parameters times bytes per parameter at your chosen quantization) plus the KV cache (which grows linearly with context length), plus roughly 10% runtime overhead. It matches what serving stacks like vLLM report in practice within a few percent.

Why do MoE models need so much memory when few parameters are active?

Active parameters set compute speed, not memory. All experts must be resident, so a 1.6T-parameter MoE needs the full 1.6T parameters' worth of memory even though only about 49B are active per token.

Does 4-bit quantization hurt quality?

Modern 4-bit methods cost a small, usually acceptable amount of quality for a 4x memory saving. 8-bit is near-lossless. For production judgment tasks, test on your own evaluations before committing.

What if the model doesn't fit any GPU I have?

You can shard across multiple GPUs (with overhead), pick a smaller model, or run it on managed inference. Allocate serves every model on this list token-metered, so idle hardware costs you nothing.

Is this calculator free?

Yes, free and unlimited, no account needed. It runs entirely in your browser.

More free tools

If it doesn't fit your hardware, it fits ours. Allocate runs every open-weight model here, token-metered, inside your own boundary; no GPUs to buy, no idle burn.