How to calculate the area of a rectangle?

I urgently need to calculate the area of a rectangle, and I can't figure out how to do it. I have long forgotten the school program. Who can tell me by what formula it is calculated? Or advise, please, some calculator on the Internet, which is programmed to calculate areas.

It is very straightforward to determine the area of a rectangle, just times its width by its total depth and you will get the result you need, and this formula is very easy to memorize. But, however, if you need this solution is not for exams at school or university, then in fact it you do not need it, as you can calculate the area of any figure with the help of area calculator, which you will find at this link https://www.calculator.io/area-calculator/.