Irrigation Timing Calculator
Turn a weekly watering target and your system’s measured application rate into a concrete number of minutes to run, split across the sessions that suit your soil.
Irrigation schedule
How the schedule is worked out
Dividing your weekly target depth by your system’s application rate gives the total hours needed to deliver that much water, which is then converted to minutes and divided by the number of sessions you plan to run. A target of 1 inch at an application rate of 1.5 inches per hour needs 40 minutes total — 20 minutes twice a week, or roughly 13 minutes three times a week.
When you add an area, the tool also reports the total gallons that amount of watering represents, using the same rainfall-to-volume constant as the rain barrel calculator, which is handy for comparing how much of a zone’s water needs a rain barrel could realistically offset.
Frequently Asked Questions
What is an application rate and how do I measure mine?
It's how fast your specific sprinkler or drip system delivers water, in inches of depth per hour — and it varies a lot between a spray head, a rotor, and a drip line, so a generic number won't fit your yard. A simple catch-cup test finds it directly: set a few straight-sided containers around the zone, run the system for a fixed time (15 minutes is common), measure the average depth collected, and scale that up to an hourly rate.
Why split the weekly target into multiple sessions?
Most soils can only absorb water so fast before it starts running off the surface or pooling, especially on a slope or in clay soil. Splitting a weekly target into two or three shorter sessions, a day or two apart, usually lets more of it soak in at the root zone instead of running off or evaporating from standing water.
Where does the 1-inch-per-week guideline come from?
It's a widely cited starting point from agricultural extension services for an established, temperate-climate lawn, covering both rainfall and irrigation combined. Actual needs shift with grass or plant type, soil, shade, and especially hot or dry stretches, so treat it as a starting point to adjust, not a fixed rule for every yard.
How does the total-gallons figure relate to the rain barrel calculator?
Both tools use the same underlying conversion — one inch of water over one square foot of area is about 0.623 gallons — just applied in opposite directions: the rain barrel calculator estimates water falling onto a roof, while this one estimates water you're deliberately applying to a garden or lawn area.
Planning estimate only. Actual watering needs vary with plant type, soil, shade, and weather; adjust the schedule to what your lawn or garden actually shows.