Adding topsoil to your backyard can be a quick way to amend the soil for a healthy lawn or garden. But a problem arises when you measure your backyard and the measurement is in square feet and the topsoil provider sells dirt in cubic yards. They are different measurements, and knowing how to convert from one to the other will ensure the right amount of soil being delivered.
Measure in feet the length and width of your yard that you want to cover in the topsoil. If it is just a section that you are working with, then just measure the section. If you are working with many small areas, break the area up into squares (or rectangles) and measure each one. Write down the measurements for each one.
Multiply each section's width by its length and write down the answers. Once you have worked every section, add up all the numbers. This is the total square feet that you want to cover in topsoil.
Decide how deep you want your topsoil to be. Two inches is a bare minimum, while 6 inches is more practical and 8 is premium coverage. If you lay 6 inches of topsoil, it will settle to about 5 inches, which is still deep enough for a good root structure for most lawns and plants. This depth will also suffocate most plants growing below as in an old lawn or weedy area.
Multiply the total of square feet you are covering with the number of inches of topsoil converted into decimal feet. For instance, 6 inches is 0.5 feet, while 8 inches is 0.66 feet and 2 inches is 0.16 feet. This calculation is done by dividing the number of inches you want in depth by the number of inches in a foot, 12. The resulting decimal can be plugged into your calculator. The answer from the multiplication will be the number of cubic feet you need.
Take the number of cubic feet and divide it by 27, which is the number of cubic feet in one cubic yard. A simple formula is CF/27 =CY where CF equals cubic feet and CY equals cubic yard. Round your answer up to the nearest whole yard (or half yard if your supplier allows).