Use the tape measure to measure the length of the area. Measure at the longest part of your lawn.
Measure the width of the area at the widest point.
Multiply the width by the length to determine the square feet. If your lawn measures 15 feet by 19 feet, for instance, you'd multiply 15 by 19 for a total of 285 square feet.
Calculate the square yards by taking the square feet and dividing by nine. If you have 285 square feet, for example, and divide by nine, the result is 31.66 square yards.