Calculators / Sprinklers
How long should you run your sprinklers?
Spray heads and rotors put down water at very different speeds. Tell us which you have, your soil and how often you water, and get the minutes for each zone.
Updated · How we check our numbers
Run each zone
19 min
2 days a week, split into 3 runs of 7 min. That puts down 0.50 in each time.
- Each zone
- 19 min3 × 7 min
- Water rate
- 1.60 in/hr
- Per watering
- 0.50 in
- Days
- 2 a week
- Soil soaks up
- 0.25 in/hr
As an Amazon Associate we earn from qualifying purchases.
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.
Lay out the headsSpacing, nozzles and the water rate for a rectangle of lawn
water to add = 1 in a week
per watering = 1 ÷ 2 days = 0.50 in
run time = 0.50 × 60 ÷ 1.60 in/hr = 18.8 min
1.60 in/hr is faster than loam or silt loam soaks up (0.25 in/hr): 3 cycles of 7 min
Set the controller to run each zone 3 times for 7 min, with 30 minutes to an hour between, so the water soaks in instead of running off.
Run a zone and time how long until water pools or runs to the sidewalk. That's your longest cycle. Shorter if the ground slopes.
Rain Bird MPR nozzles at 30 psi run 1.52 to 1.74 in/hr. Your heads may differ: set out tuna cans, run the zone 15 minutes, and put the average depth in here.
Water before sunrise. Less blows away and evaporates, and the grass dries off during the day.
How we work it out
Most lawns need about an inch of water a week, counting rain. Split that over your watering days, then divide by how fast your heads put water down:
minutes = inches per watering × 60 ÷ inches an hour
Typical rates from Rain Bird's charts: spray heads about 1.6 inches an hour, rotors and rotary nozzles about 0.6, small rotors about 0.5. Yours depend on spacing and pressure, so a can test is better.
Can test. Set six or more straight-sided cans (tuna cans work) around the zone, run it 15 minutes, then average the depth:
inches an hour = average depth × 60 ÷ minutes run
Cycle and soak. Spray heads put water down faster than most soil takes it in. Basic intake rates from the University of Nebraska: about 0.5 in/hr for fine sand, 0.35 for sandy loam, 0.25 for silt loam and 0.1 for clay. When the heads are faster, we split the run into up to four cycles of at least five minutes, the Irrigation Association's guide for fine soils. Leave 30 minutes to an hour between cycles, as the EPA suggests.
How much at once. Clemson Extension says to put down about half an inch at a time on sandy soil, and an inch on heavier soil. Water past that drains below the roots, so sandy lawns get watered more often.
Where the numbers come from
- EPA WaterSense: watering tips
- EPA WaterSense: cycle and soak (PDF)
- Clemson HGIC 1207: watering lawns
- Iowa State Extension: home lawn watering
- Irrigation Association: landscape irrigation best management practices
- University of Nebraska: irrigation tables (soil intake rates)
- Rain Bird 5000 MPR rotor nozzle chart (0.6 in/hr)
Upgrade the timer
Nozzle charts
Sprinkler planning
More calculators
- Smart controller savingsHow much will a smart sprinkler controller save?
- Sprinkler zonesHow many zones will my water pressure run?
- Water pressure and flow testWhat gpm and psi does my hose bib give me?
- Sprinkler layout plannerWhere do the heads go, and how many?
- Rainwater collectionHow many gallons will my roof collect?
- Rain garden sizeHow big should my rain garden be?
- French drainHow much gravel and pipe for a French drain?
- Dry well sizeHow big a pit for my downspout?