Luxor4u

I've had a number of adverts come across my screen recently regarding zakat, one of which mentioned a zakat calculator.
I could be wrong about this but I think zakat is to do with Islamic charitable giving. If so, why would a calculator/calculation be required?
Would someone enlighten me please.

In Saudi Arabia zakat is calculated at approximately 15% of yearly profit. The act of charitable giving (zakat) is one of the pillars of Islam.

Possibly the calculator is just a clever marketing tool via capitalistic influences creeping into the Muslim world.