Sprinkler Watering Schedule Calculator
Turn a weekly watering target into per-session sprinkler run times, and see the gallons your lawn uses each week.
How it works
Weekly minutes = (weekly inches ÷ output in/hr) × 60 · Per session = weekly minutes ÷ watering days · Weekly gallons = area × inches × 0.623
Grass needs a set depth of water per week — about an inch for most lawns — and your sprinklers apply water at a certain rate in inches per hour. Dividing the target depth by that rate gives the total run time, which you then split across your watering days. Fewer, deeper sessions encourage roots to grow down, so two or three longer runs beat daily sprinkling; a catch-cup test is the reliable way to learn your true output rate.
Worked example
A lawn needing 1 in a week watered by 1.5 in/hr spray heads needs (1 ÷ 1.5) × 60 = 40 minutes of total run time. Split over three days that is about 13 minutes per session. On 1,000 sq ft, 1 inch of water is roughly 623 gallons for the week.
Frequently asked questions
How long should I run my sprinklers?
Divide your weekly water target (about 1 inch for most lawns) by your sprinkler’s output rate in inches per hour to get total minutes, then split that across your watering days. Spray heads finish far faster than low-output rotors.
How do I find my sprinkler’s output rate?
Do a catch-cup test: place several straight-sided containers around the zone, run it for 15 minutes, measure the average depth collected, and multiply by four to get inches per hour. It is more accurate than any manufacturer estimate.
Is it better to water more often or more deeply?
Deeply and less often. Two or three longer sessions a week push roots to grow downward, making the lawn more drought-tolerant, while daily light watering keeps roots shallow and weak. Water early morning to cut evaporation.
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This calculator is for educational purposes. Double-check important results before acting on them.