How to Measure an Area for Materials
To measure an area for materials, multiply length by width for a rectangle, or use 3.1416 times the radius squared for a circle. For irregular shapes, split the space into rectangles and circles, measure each, and add them together. Once you have the total square footage, a depth turns it into cubic yards.
Rectangles and circles
For a rectangle, area equals length times width, both in feet. For a circle, the area is 3.1416 times the radius squared, where the radius is half the diameter.
Measure in feet and keep a consistent unit. A tape measure or a measuring wheel for big areas both work.
Irregular and L-shaped areas
Break the space into simple shapes. An L-shaped patio is two rectangles; a curved bed can be approximated as a rectangle plus a half-circle on the end.
Calculate each piece, add them up, then take the total into the material calculator. When in doubt, round the area up a little so you do not come up short.
FAQ
How do I measure an irregular garden bed?
Split it into rectangles and partial circles, measure and calculate each, then add them. Rounding the total up slightly avoids running short.
How do I find the area of a circle?
Multiply 3.1416 by the radius squared. The radius is half the diameter, both measured in feet.