What's Figma's measuring unit?

I know that Figma has a lot of presets fo a bunch of frames, but if I want to create a design that I can measure in mm, the relaion is not 1:1. Could somebody give me any guide or standard measurement so I can change the sizes myself please?

Hey Agustín, thanks for reaching out!

Figma’s default measurement unit is the pixel. Figma layouts and components are specified in pixels.