Drip Irrigation Calculator

Drip systems deliver water slowly at each plant, so the question is how long to run them. Enter your emitters and how much water each plant needs to get run time, total flow and weekly use.

View formula

Run time (min) = water per emitter ÷ emitter flow × 60 Zone flow (GPH) = emitters × emitter flow Zone flow (GPM) = GPH ÷ 60 Works the same in L/h and litres.

How to use the Drip Irrigation Calculator

Count the emitters on the zone and choose their flow rate (printed on the emitter).
Enter how much water each plant should get per session.
Enter sessions per week.
Optionally add your supply flow to check the zone isn’t too large.

Drip irrigation formulas

Minutes = gallons per plant ÷ GPH × 60 Zone GPH = emitters × GPH per emitter

Worked example

20 emitters at 1 GPH, each plant needing 0.5 gal per session, 3 times a week:

Run time: 0.5 ÷ 1 × 60 = 30 minutes
Zone flow: 20 × 1 = 20 GPH (0.33 GPM)
Weekly water: 20 × 0.5 × 3 = 30 gallons

How much water does each plant need?

Needs vary with plant size, soil and weather. As a starting point, many gardeners give small vegetables and annuals around 0.25 to 0.5 gal per session and large shrubs several gallons. Check moisture with a finger or trowel a few inches down and adjust run times until the root zone is moist but not soggy.

Sizing a zone

Keep the total zone flow comfortably below your supply flow, splitting large zones keeps pressure even.
Every tubing size has a maximum flow and run length; check the manufacturer’s chart for your tubing.
Use pressure-compensating emitters on slopes or long runs so every plant gets the same amount.

FAQ