# Free GPU calculators

> Size the GPU memory a model needs and compare a monthly server with any hourly price.

Source: https://overgpu.com/tools  
Publisher: OverGPU (https://overgpu.com/)

## Pages

- [GPU cost calculator: monthly vs hourly GPU rental](https://overgpu.com/tools/gpu-cost-calculator): Use this GPU cost calculator to compare hourly and monthly GPU rental: monthly totals, break-even hours and the extra costs to count before you decide.
- [LLM VRAM calculator: will your model fit on a GPU?](https://overgpu.com/tools/vram-calculator): Free LLM VRAM calculator: pick Llama, Qwen, Mistral or gpt-oss, set the precision and context length, and see weights, KV cache and which GPUs fit.

## Size the model first, then compare the price

Two questions decide which GPU server to rent: how much memory your model needs, and whether a monthly price beats an hourly one at your usage. The two **free GPU calculators** answer them in that order.

1. **Size it with the [VRAM calculator](https://overgpu.com/tools/vram-calculator).** Pick a model or enter its size, choose the precision (BF16, FP8 or 4-bit), the context length and the number of concurrent requests. It adds up weights, KV cache and runtime overhead and lists every configuration that fits, with its monthly price.
2. **Budget it with the [GPU cost calculator](https://overgpu.com/tools/gpu-cost-calculator).** Enter any hourly price and how many hours a day the GPU will really run. It shows the monthly cost at that rate, the break-even hours against a monthly server and the cost per hour you actually use.

Both run in your browser, need no account and send nothing to us. For the reasoning behind the numbers, read [how much VRAM an LLM needs](https://overgpu.com/blog/vram-for-llms) and [monthly vs hourly GPU pricing](https://overgpu.com/compare/monthly-vs-hourly-gpu-pricing).

## How accurate the estimates are

The VRAM figures come from the model's architecture: parameters times bytes per parameter for the weights, plus a KV cache computed from layers, KV heads and head size, plus a margin for activations and the runtime. Real usage varies with the serving engine, batch size and memory settings, so treat the result as a sizing guide and keep 10 to 20% headroom. The cost calculator is exact arithmetic on the prices and hours you enter.

## GPU calculator FAQ

### Are the GPU calculators free?

Yes. Both calculators are free, run entirely in your browser and need no account or email.

### How do I know which GPU my model needs?

Use the VRAM calculator: choose the model, precision, context length and concurrency, and it lists the configurations with enough memory, from a single GPU to an 8-GPU server.

### How do I compare a monthly GPU server with an hourly price?

Enter the hourly price and your daily usage in the GPU cost calculator. It shows the break-even number of hours: above it, the monthly server costs less; below it, hourly billing does.