The number of brick required is based on the actual size of the brick. The larger the brick the fewer number of brick required. Add up the total surface area of the wall. Subtract out windows and doors and throw in a value for waste. Most installers assume that an additional 5% should be added to cover waste. The web calculator will provide th is information. The calculator can break up the wall area into rectangular sections. A maximum of 8 sections are allowed. If you have more sections that 8, try running the calculator multiple times as required and add the quantities by hand. Refer to wall calculator on the web.