How to Calculate Lawn Sprinkler Heads

Measure the length and width of the lawn. Multiply the length and the width to get the square footage of the lawn.

Draw the lawn area on a piece of paper, using one-quarter scale --- that is, 1 foot equals 1/4 inch.

Select the type of sprinkler head that is best-suited to your lawn. There are two main spray types: those that spray 180 degrees and those that spray 360 degrees.

Inspect the package for the length of spray for each individual sprinkler. This spray length is probably a bit high, since the sprinklers were likely tested indoors. You will need to install the sprinklers closer than recommended.

Divide the scale drawing of your lawn into squares slightly smaller than the size of the spray length.

Draw a sprinkler head in the center of each square. Use a compass to draw the spray length from the center of the sprinkler head. Make sure the spray lengths overlap. This is the final number and placement of sprinkler heads needed.