Free sprinkler coverage calculator. Enter lawn area and coverage per sprinkler to find how many sprinklers you need and total coverage.
Your results will appear here.
Enter your values and press Calculate.
Divide lawn area by the coverage of one sprinkler and round up, since part of a sprinkler cannot water a lawn. Total coverage is sprinklers needed times coverage per sprinkler, which should be at least the lawn area.
A 2000 square foot lawn with sprinklers covering 400 square feet each needs 5 sprinklers, giving exactly 2000 square feet of coverage. A 1500 square foot lawn with 500 square foot sprinklers also needs 3 sprinklers. This sprinkler system calculator is an irrigation planning tool for lawn irrigation systems.
Coverage per head is the area one head waters, often 400 to 800 square feet for a standard head with a 25 to 30 foot diameter. For a circular spray pattern, area is pi times radius squared, so a head with a 15 foot radius covers about 707 square feet before overlap. Use the maker coverage figure from the box when you have it, since it already accounts for the spray pattern.
Coverage maths gives heads for the whole lawn, but zones limit how many heads run at once. Divide your water supply in gallons per minute (GPM) by GPM per head, rounding down, and leave a 10 to 15 percent safety margin. At 30 PSI a head may use 2 GPM, at 40 PSI about 3 GPM, and at 50 PSI about 4 GPM, so higher pressure does not always mean more heads per zone.
Space heads so spray patterns overlap by about half, called head to head coverage, so every spot gets water from more than one head. A common spacing rule is to place heads one radius apart, not one diameter apart, which doubles coverage in the overlap zones and prevents dry patches. Round spray patterns on square lawns always leave corners to plan for.
Spray heads suit small lawns and beds, covering a few hundred square feet each at 20 to 30 PSI with 1 to 3 GPM. Rotor heads suit medium and large lawns, throwing 15 to 50 feet at 30 to 50 PSI with 2 to 5 GPM, and rotary nozzles suit slopes and water saving with low flow. Do not mix rotor and spray heads on one zone, since their watering rates differ and one area will overwater while another stays dry.
Split irregular lawns into rectangles, circles and strips, calculate each part separately, and add the heads together. Place heads along edges and corners first, then fill the middle, keeping spray off paths and driveways. Narrow strips need strip pattern nozzles rather than full circle heads, or much water lands on paving.
A 2400 square foot lawn with heads covering 500 square feet each needs 2400 / 500 = 4.8, rounded up to 5 sprinklers, giving 2500 square feet of total coverage. If your supply supports only 4 heads per zone at your PSI and GPM, split the lawn into two zones rather than starving heads of water.
Ignoring overlap leaves dry patches even when total area maths looks right. Mixing head types on one zone, ignoring pressure loss through pipes and elevation, and spacing heads by diameter instead of radius are the most common errors. Measure lawn area, check head coverage from the maker, and verify PSI and GPM with a gauge and bucket test before buying.
Space heads so their spray patterns overlap by about half, which is called head to head coverage. Gaps between sprays leave dry patches even when the total area maths looks right.
It depends on the head type and water pressure: small fixed heads cover a few hundred square feet, while rotor heads can cover over 1000 square feet each.
Divide your supply GPM by GPM per head and round down, leaving a 10 to 15 percent margin. For example, 12 GPM with 2.5 GPM heads gives 4 heads per zone, so a 12 head lawn needs 3 zones.
Break the lawn into rectangles and circles, measure each part, and add them. For a rectangle multiply length by width; for a circle use pi times radius squared. Graph paper with one square per square foot helps for curved edges.
Most home systems work best at 30 to 50 PSI. Below that, spray falls short; above it, misting wastes water. Measure at an outdoor faucet with a pressure gauge and use the lowest reading.
Rotor heads suit large lawns, since they throw further and use water more slowly over a larger area. Spray heads suit small lawns and beds where short, even coverage matters more than distance.
Aim for head to head overlap, where each head sprays to the next head. That is about 100 percent overlap in spacing terms, and it compensates for wind and uneven spray.
Usually spacing or pressure is wrong: heads too far apart, pressure too low, or mixed head types on one zone. Check spacing, PSI and head GPM, and look for clogged nozzles.
It is not recommended. Rotors and sprays apply water at different rates, so one part of the zone overwater while another stays dry. Keep each zone to one head type.
Do a bucket test: time how long an outdoor faucet takes to fill a 5 gallon bucket, then divide gallons by minutes for GPM. For example, 5 gallons in 1 minute is 5 GPM.