The gist of it is that you need a way to measure the difference between your income and the amount you earn, as opposed to a standard income measure.
The calculator will ask you to enter the amount of money you earn in terms of a standard, everyday wage.
It will then calculate the difference, which is then added to your income to give you a standard gross income.
This is the best way to calculate your gross income for the purpose of calculating your income tax and social security contributions.
For more information on how to use this calculator, click here.