Sprinkler Run Time Calculator
Enter lawn area, what your sprinklers actually put out and the weekly goal. The calculator returns minutes per zone, the watering days that prevent runoff, and the gallons behind the plan.
Most sprinklers run too long and too often: the grass needs about an inch a week, split so it soaks in, delivered before the sun steals it. The missing number is your real output - the box claim is usually double - and the tuna-can calibration in the notes settles it in fifteen minutes.
How to use
- Lawn area first - the gallons figure scales straight off it.
- Real output in inches per hour: calibrate with cans, do not trust the box.
- Pick the weekly goal and soil type - clay and sand split the schedule differently. All four update live.
Frequently asked questions
How long should I run my sprinklers?
Divide the weekly inch goal by your measured output, then split across days: at 1.5 inches per hour, one inch a week is about 20 minutes a zone, twice a week. The calculator runs the division with your real numbers instead of a neighbor guess.
How do I measure my sprinkler output?
Tuna cans or any straight-sided containers spaced across a zone, run 15 minutes, measure depth, multiply by four for inches per hour. Average the cans - heads overlap unevenly, and the dry spot tells you which head needs adjusting more than the math does.
Is it better to water deeply or daily?
Deeply and infrequently, every time: one or two soakings grow roots downward, while daily sprinkles keep roots at the surface where August heat finds them. Clay soils split into two slower runs so water soaks instead of sheeting off; sand needs three short ones.
What time of day should I water the lawn?
4 to 8 in the morning: evaporation is lowest and the blades dry by noon, which prevents the fungal diseases evening watering invites. Midday wastes a third of the water to the sky before it reaches the roots.