Use a measuring tape to measure the length and width of the pour area that you wish to cover with cement. Decide how thick you want the finished cement project to be. Make sure that all three of your measurements are in the same units, usually feet or inches.
With a calculator or a pencil and paper, multiply the three numbers from Step 1 together. This is the total fill area. Write this number down and take it with you to a hardware or home improvement store.
Choose a cement product and examine the packaging to find out how much area one container of that particular product will cover, since different packages will contain different amounts of products and different brands will cover different areas.
Purchase enough of the cement to add up to the total fill area that you wrote down on your paper.