How do Hybrid Vehicles Calculate Range?

[patrickhays2]

I drive a 2018 Kia Niro LX with the Tech Package; I've put a little over 3,000 miles on it.

Can anyone provide insight as to how a hybrid vehicle calculates predicted range? The estimated range swings 20-30 miles up or down every fuel-up. It's been as high as an estimated 593 miles and as low as 530 miles.

Does this technique change based on the manufacturer? Is the technique the same in non-hybrid cars as well? It might be too general of a question, but maybe someone can point me in the right direction.

Thanks!