Sprinkler Run-Time Calculator
Turn the results of a catch-cup test into how many minutes to run each sprinkler zone, and see how evenly your sprinklers water.
Place straight-sided containers around the zone, run it for a set time, then measure the depth of water in each with a ruler. How to do a catch-cup test
Run time for this zone
Enter at least two cup readings, the test time and the water you want to apply.
How it works
Sprinkler run times are usually guesses. A catch-cup test replaces the guess with a measurement: set out containers, run the zone, and measure what they caught. This calculator turns those readings into run times and tells you whether some parts of the lawn are getting much less water than others.
Worked example
Four cups collected 4, 5, 6 and 5 mm in 15 minutes. Average: 5 mm, so the zone applies 20 mm an hour. To apply 10 mm, run it for 30 minutes. The lowest cup is 80% of the average, which is fairly even coverage.
What you enter
- Water depth in each cup (mm)
- How long the test ran (minutes)
- How much water you want to apply (mm)
What you get
- Average application rate (mm per hour)
- Minutes to run for your target
- How evenly the zone waters
Assumptions
- Use straight-sided containers so depth equals rainfall-equivalent millimetres.
- Evenness is measured as the average of the lowest quarter of cups divided by the overall average.
Questions
How many cups do I need?
At least six spread across the zone gives a useful picture. More is better on large or oddly shaped zones.
How much water should I apply?
It depends on your grass, soil and weather. See How much water does my lawn need, and always follow your local water rules.