Sprinkler Run Time Calculator
Works out how long to leave the sprinklers on.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
rate = cup depth × 60 ÷ test minutes, or head flow ÷ (head spacing × row spacing) minutes = (depth wanted − rain) ÷ efficiency ÷ rate × 60
A litre on a square metre is a millimetre, so flow over the area each head serves gives a depth per hour.
What to watch out for
A catch-cup test is the more trustworthy route, as it measures your actual pressure and layout. To lay out the heads and count them, use the sprinkler coverage calculator.
Frequently Asked Questions
How long should I water a lawn?
If cups collect 6 mm in 15 minutes, the rate is 24 mm/h. 25 mm a week at 75% efficiency takes 83 minutes in total.
Is it better to water often or deeply?
Deeper and less often generally encourages deeper roots, as long as the soil can absorb it without runoff.