Plant Watering Calculator
Turn a weekly watering depth over your garden area into gallons and litres per week, and per watering session. Calculates in your browser.
Water per week
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Show the math
One inch of water over a square foot is about 0.623 gallons:
gallons/week = area × inches × 0.623
Most vegetable gardens want roughly an inch of water a week, including rainfall. Deep, less-frequent watering encourages stronger roots than daily sprinkling. All math runs locally in your browser.
What this does
A plant watering calculator turns a weekly watering depth over your garden area into gallons and litres per week, and per watering session.
How to use it
- Enter the garden area.
- Enter the weekly watering depth.
- Set the sessions per week.
- Read gallons per week and per session.
How it works
About 0.623 gallons covers a square foot an inch deep. Many gardens want roughly an inch a week, including rainfall.
gallons = area × depth (in) × 0.623
Understanding your result
Most gardens want about an inch of water a week including rainfall, so subtract recent rain before topping up. Deep, less frequent watering encourages roots to grow down and makes plants more drought-tolerant than a daily light sprinkle that keeps moisture near the surface.
Example
An inch of water over 100 sq ft is about 62 gallons a week.
Sources & methodology
Last updated .
Frequently asked questions
How much water does a garden need?
Many vegetable gardens want roughly an inch of water a week, including rainfall, but this varies with heat, soil, and crop.
How many gallons is an inch of water?
About 0.623 gallons covers a square foot an inch deep, so an inch over 100 sq ft is roughly 62 gallons.
Is it better to water deeply or often?
Deep, less-frequent watering encourages stronger, deeper roots than light daily sprinkling, which keeps roots shallow.
Is anything stored?
No. Everything is calculated locally in your browser.
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