Drip Irrigation Run Time Calculator
How long to run a drip zone to deliver the water your plants need — from emitter flow rate, emitters per plant, plant water requirement or bed area and mm per week — with weekly schedule and zone flow check.
How it works
Minutes = (weekly litres ÷ days per week) ÷ (emitters × L/h per emitter) × 60; area mode: weekly litres = mm × m²; zone flow = plants × emitters × L/h
Drip irrigation puts water where roots are at a rate the soil can absorb, but its slow trickle means run times are measured in tens of minutes to hours, not the few minutes a sprinkler takes. Start from what the plant needs each week — a fruiting tomato wants around 20 litres, established shrubs more, and vegetable beds as a whole about 25 mm (25 litres per square metre) — divide by the number of watering days, then by the combined output of the emitters serving that plant. Fewer, longer, deeper waterings beat daily sips for most crops because they push roots down. Add up the emitters to check the zone does not exceed what your tap, filter and tubing can supply, and adjust with the weather rather than the calendar.
Worked example
20 L per tomato plant a week from two 4 L/h emitters, three days a week: 6.7 L per session ÷ 8 L/h = 50 minutes. Twelve plants draw 96 L/h while running.
Frequently asked questions
How many emitters per plant?
One for small vegetables and pots, two on opposite sides for tomatoes and shrubs, four to six around the drip line of a tree, added as it grows.
Why does the far end of my line get less water?
Pressure drops along long runs; use pressure-compensating emitters, keep laterals under 60–90 m (13 mm tube), and install a 1.0–1.5 bar pressure regulator and filter at the head.
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This calculator is for educational purposes. Double-check important results before acting on them.