Garden Watering Schedule Calculator

About this calculator

Most garden plants need a fairly consistent amount of water per week to thrive — commonly cited as about 1 inch of water per week for lawns and vegetable beds, with adjustments for thirstier or drought-tolerant plant types. This calculator converts that weekly depth requirement into actual gallons based on your garden's area, then subtracts what recent rainfall already provided.

The core conversion is gallons needed = inches of water × area (sq ft) × 0.623 — the constant comes from 1 inch of water over 1 square foot being 0.623 gallons. If your area needs 1 inch a week and you've already had 0.4 inches of rain, you only need to irrigate the remaining 0.6 inches' worth.

Home gardeners use this to avoid both underwatering (stressed, shallow-rooted plants) and overwatering (wasted water, root rot, runoff) by tailoring a watering schedule to actual weekly rainfall rather than watering on a fixed calendar regardless of recent weather.