It is a calculator that will allow you to calculate an approximate amount of brick, sand and contrite to use in the construction of a wall. At the time of the calculation, it will always be considered a 5% waste. If you need more references of the values taken for the calculation, visit the following link: http://www.acerosarequipa.com/manual-del-maestro-constructor/procedimientos-basicos/aportes-de-materiales.html