Calculators / Sprinklers
Sprinkler layout planner
Measure a rectangle of lawn and pick a head type. You get a to-scale drawing with every head, the nozzles to buy, the gpm and how fast the water goes down.
Updated · How we check our numbers
Lay it out like this
12 spray heads
4 by 3 grid over 1,000 sq ft, using Rain Bird MPR 15 series, in 3 zones. Water goes down at 2.14 in an hour.
- Heads
- 12Rain Bird MPR 15 series
- Spacing
- 13.3 ftmax 15 ft
- Water rate
- 2.14 in/hr
- Zones
- 322.2 gpm total
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Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.
How long to water2.14 in/hr, your soil and the week's need
max spacing = 50% of 30 ft throw diameter = 15 ft (wind 4 to 7 mph)
heads along 40 ft = 4, 13.3 ft apart; across 25 ft = 3, 12.5 ft apart
heads = 4 corners + 6 edges + 2 inside = 12
flow = 4 × 0.92 + 6 × 1.85 + 2 × 3.7 = 22.2 gpm
water rate = 96.3 × 3.7 gpm ÷ (13.3 × 12.5 ft) = 2.14 in/hr
usable flow = 10 gpm × 75% = 7.5 gpm
zones = 22.2 ÷ 7.5 = 3, rounded up
12 heads, 13.3 ft apart along the length and 12.5 ft across. Shaded slices are each head's throw.
Heads to buy
30 psi chart- 4 quarter circlesRain Bird MPR 15 series, 0.92 gpm eachCorners
- 6 half circlesRain Bird MPR 15 series, 1.85 gpm eachEdges
- 2 full circlesRain Bird MPR 15 series, 3.7 gpm eachInside
Flow is the maker chart figure at the chart pressure. Buy a couple spare nozzles in each arc.
Sprays work best at 30 psi. Rain Bird 1800 PRS bodies hold 30 psi at the nozzle, so they don't fog at your pressure.
Set each nozzle to throw 13.3 ft with its adjusting screw, so it reaches the next head without watering the sidewalk. Flow drops a little too, so the real water rate runs a bit under ours.
2.14 in/hr is faster than clay or loam soaks it up. Split each watering into short cycles with a soak between.
Quarter, half and full nozzles in one series put down the same inches an hour, so they can share a zone. Don't mix sprays and rotors on one zone.
Every head's throw should reach close to its neighbours. Stretching the spacing to save heads leaves dry spots in the middle of each square.
How we work it out
Heads go in every corner as quarter circles, along every edge as half circles, and inside as full circles. Each head's throw should reach close to its neighbours, which installers call head to head.
Rain Bird's design manual sets how far apart heads can go, as a share of the throw diameter, by the wind when you water: 55% when calm (0 to 3 mph), 50% in a light breeze (4 to 7 mph) and 45% when windy (8 to 12 mph).
max spacing = wind share × 2 × nozzle radius
heads along a side = side ÷ max spacing, rounded up, + 1
We try every nozzle size in the family and keep the layout with the fewest heads. The nozzle screw can turn a radius down by up to 25%, so we set the throw to just what the spacing needs.
The water rate uses Rain Bird's formula. One full circle's worth of water lands on each square of the grid:
inches an hour = 96.3 × full-circle gpm ÷ (spacing × row spacing)
Nozzle flows come from Rain Bird charts: MPR spray nozzles at 30 psi, 3500 rotors and 5000 MPR rotor nozzles at 45 psi. Quarter, half and full nozzles in one series put down about the same inches an hour, so they share a zone. Zones use 75% of your bucket-test flow.
Odd shapes: split the lawn into rectangles and plan each one. Triangle spacing covers curved edges better, but on a straight-edged rectangle a square grid is simpler and puts heads right on the edges.
Where the numbers come from
Nozzle charts
Sprinkler planning
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