Drip Irrigation Run Time Calculator
How long to run a drip zone to give each plant, or a whole bed, the water it needs.
Result
Enter water per plant to see the result.
https://calcgallery.com/landscaping/drip-irrigation-run-time-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use the Drip Irrigation Run Time Calculator
- Choose whether you know the water each plant needs or a depth of water for a whole bed.
- Enter that amount, the emitters per plant or in the bed, and each emitter's flow from its packaging.
- Read the run time for one watering and the zone's total flow.
- Enter your tap's or valve's flow under More options to see whether the zone needs splitting.
How it is calculated
water per plant mode: flow per plant = emitters per plant × emitter flow run time = water per plant ÷ flow per plant zone flow = plants × flow per plantbed mode: water = bed area × depth of water zone flow = emitters × emitter flow run time = water ÷ zone flowzones = ⌈zone flow ÷ supply flow⌉The page works in any units: gallons and gallons per hour, litres and litres per hour, or a mix, since everything is converted before dividing.
Checking the figures
Emitter ratings assume the pressure the maker specifies; a pressure regulator and filter at the head of the zone keep them close to it. To check a real zone, run it into a container for a set time, or catch one emitter’s water in a measuring jug for a minute. The run time here is for one watering; how often to water depends on the plants, the soil and the weather.
With your numbers
- Each plant gets 2 × 1 gph = 2 gph
- Run time = 1 gal ÷ 2 gph = 30 min
Quick reference
Arithmetic from your figures; hot, windy or sandy conditions can call for more water than you planned.
| Job | Run time |
|---|---|
| 1 gal per plant, two 1 gph emitters | 30 min |
| 2 gal per shrub, two 1 gph emitters | 60 min |
| 5 gal per tree, four 2 gph emitters | 38 min |
| 36 gal per vine, two 0.48 gph emitters | 2,250 min |
| 1 in over a 100 sq ft bed, 50 emitters | 75 min |
| 1 in over 250 sq ft, 100 × 0.27 gph | 346 min |
| 4 L per plant, two 2 L/h emitters | 60 min |
| 20 mm over 10 m², 50 × 2 L/h | 120 min |
Common questions about the Drip Irrigation Run Time Calculator
- How long should I run my drip irrigation?
- Divide the water a plant needs by the water its emitters deliver in an hour. UC ANR’s microirrigation guide works a vineyard example this way: 36 gallons a vine a week through two 0.48 gallon-an-hour emitters is 37.5 hours of irrigation. The same arithmetic gives minutes for a garden bed and hours for a tree.
- How do I convert inches of water to gallons?
- One inch of water over one square foot is 144 cubic inches, which is 0.623 US gallons, since a gallon is 231 cubic inches. So a bed of 100 square feet needs about 62 gallons for each inch. In metric, 1 mm of water over 1 m² is exactly 1 litre.
- How much water does a plant need?
- That depends on the plant, its size, the soil and the weather, so the page leaves it to you. Extension services publish guides for vegetables, shrubs and trees in each region.
- Why do the emitters at the end of the line drip less?
- The zone may ask for more water than the supply gives. Add up every emitter’s flow, which the page shows as the zone flow, and compare it with what the tap delivers by timing how long it takes to fill a bucket. Pressure-compensating emitters hold their rated flow only within their pressure range.