Irrigation Timer Calculator
Calculate sprinkler or drip irrigation run time from area and plant water needs in inches per week.
Returns minutes per cycle and gallons used per zone.
Watering Schedule
Irrigation timing determines how long to run your watering system to deliver the right amount of water. Too little causes drought stress. Too much wastes water and promotes root rot.
The formula:
Run Time (minutes) = (Water Needed in inches / Application Rate in inches per hour) x 60
Water needs by plant type:
| Plant Type | Inches Per Week | mm Per Week |
|---|---|---|
| Lawn (cool season) | 1.0-1.5 in | 25-38 mm |
| Lawn (warm season) | 0.75-1.0 in | 19-25 mm |
| Flower beds | 1.0-1.5 in | 25-38 mm |
| Vegetable garden | 1.0-2.0 in | 25-50 mm |
| Shrubs (established) | 0.5-1.0 in | 13-25 mm |
| Trees (established) | 0.5-0.75 in | 13-19 mm |
Application rates by system type:
- Rotary sprinklers: 0.5-1.0 in/hour (13-25 mm/hr)
- Fixed spray heads: 1.0-2.0 in/hour (25-50 mm/hr)
- Drip irrigation: 0.5-1.0 in/hour (13-25 mm/hr)
- Soaker hose: 0.5-1.0 in/hour (13-25 mm/hr)
Soil type matters:
- Sandy soil absorbs water fast but does not hold it long. Water more frequently, shorter duration.
- Clay soil absorbs slowly but holds water longer. Water less often but for longer with breaks to prevent runoff.
- Loam is ideal and absorbs at a moderate, even rate.
Best time to water: Early morning (6-10 AM) minimizes evaporation and fungal growth.