💧Garden Watering Calculator
sq ft
inches

Weekly Water Needs

Water to apply—
Total weekly need—
Rainfall covers—
Equivalent depth—
Free companion spreadsheet
Track your results season to season
Download .xlsx

Related Calculators

How Much Water Does a Garden Need?

Most vegetable gardens need 1 inch of water per week — either from rain or irrigation. One inch of rain over one square foot equals about 0.623 gallons.

The formula

Gallons needed = Area (sq ft) × Depth (inches) × 0.623

This calculator adjusts for crop type and climate multiplier, then subtracts expected rainfall to give you just the irrigation amount.

Water needs by crop

CropInches / week
Tomatoes1.5 – 2
Lettuce, spinach1 – 1.5
Cucumbers1.5
Beans1
Corn1.5 – 2
Herbs0.5 – 1
Root vegs0.75 – 1
Best time to water: Early morning (6–10 AM) reduces evaporation and prevents fungal disease. Avoid evening watering which leaves foliage wet overnight.