Sprinkler run time calculator

Do a quick catch-cup test, enter what you measured, and choose how much water and how many watering days you want. You'll get the minutes to set on your timer.

Water caught in the cups (inches)

Test run time (minutes)

Water needed per week (inches)

Watering days per week

–minutes per watering

Sprinkler output (in per hour): –
Total minutes per week: –
Water per session (in): –

Most lawns need about 1 inch per week, including rain.

How to do a catch-cup test

Place five or six straight-sided containers, such as tuna cans or cups, around one sprinkler zone. Run the sprinklers for 15 minutes, then measure the water depth in each container with a ruler and use the average. That number goes in the first field above.

If some cups have much more water than others, the zone waters unevenly. Check for clogged or tilted heads before adjusting the timer.

How the math works

The test shows how many inches per hour your sprinklers put down. If the cups caught a quarter inch in 15 minutes, the zone puts down 1 inch per hour. To give the lawn 1 inch per week over two days, each session needs half an inch, which is 30 minutes.

Common questions

What if water runs off before the time is up?

Split each session into two or three shorter cycles with about an hour in between. This "cycle and soak" method lets clay and sloped soil absorb the water instead of sending it down the gutter.

Is it better to water often or deeply?

Deep, less frequent watering encourages deeper roots that handle heat and drought better. Daily short watering keeps roots shallow.

What time of day should I water?

Early morning is best. Less water evaporates, and the grass dries during the day, which lowers the risk of disease.