The main idea: in order not to keep all the numbers (amount of markers, houses, shock etc.) in your head when planning the attack, you can enter them into the calculator, and it will calculate everything. Also the calculator may show the maximum damage you can cause by the gunboat.
Warriors, zookas, barage and artillery
In the lower part of the calculator it is possible to calculate maximum damage that units can cause per one second or one shoot/hit in order to know how much time it will take to destroy the HQ, Power Core or any other defense building.
The calculator also shows health of one unit, this helps to calculate how long this can hold the fire from the weaponry of one or several certain defense buildings. This can be helpful to assess the expediency of Your attack.
If you boost statues then you have to change the percentage in the respective field. As there can be many statues but you will boost only few of them it is impossible to make button which doubles the percentage.