Garden watering calculator
University of Minnesota Extension says a vegetable garden needs about one inch of water per week. This calculator turns that into gallons for your garden, subtracts the rain you got, and tells you how long to run the hose.
Calculator
Results appear here.
How to use it
- Enter the garden size.
- Enter the rain from a rain gauge or local weather report.
- Optional: time how many seconds your hose (with its nozzle) takes to fill a 5-gallon bucket.
The formula
UMN also advises watering sandy soils twice a week with half an inch each time, and checking soil moisture: if the soil is dry two inches below the surface, it is time to water. Mulch helps soil hold water.
Gear for this job
Disclosure: some links on this site may be affiliate links; if you buy through them we may earn a commission at no extra cost to you. Learn more.
- Rain gauge — [affiliate link placeholder]
- Soaker hose or drip kit — [affiliate link placeholder]
- Hose timer — [affiliate link placeholder]
- Hose flow meter — [affiliate link placeholder]
Frequently asked questions
How many gallons is an inch of water?
About 0.623 gallons per square foot, or 62 gallons per 100 square feet.
How often should I water my vegetable garden?
UMN Extension: about once a week on soils that hold moisture, twice a week on sandy soil. Check the soil — dry two inches down means water.
How do I know how much my hose puts out?
Time how long it takes to fill a 5-gallon bucket at your normal setting. If it takes 30 seconds, your hose delivers 10 gallons per minute.
Sources
- University of Minnesota Extension — Watering the vegetable garden
- University of Nebraska–Lincoln NebGuide G2220 — Rainwater Harvesting with Rain Barrels
Last reviewed 2026-10-22. Found an error? Tell us.