Earnings calculator is designed to give you an idea how much net you're earning from your work.
It automatically sums your gross earnings from all your connected gig apps, and based on your settings (age, student status, other sources of income, etc.), it counts how much social contributions and income tax you'll have to pay. Thanks to this, you're getting an estimate of how much net you're going to make this month. You can also compare how much gross you've been earning in previous months and how much net earnings did it meant.