## How much water? Inches of rain vs. gallons

Some quick calculations to relate rainfall to a watering schedule. This is pretty simple for a square-foot garden, the area of a square is one square foot. This makes some of the math really simple, too. These numbers all apply to one square foot. Just multiply by the number of square feet to figure how much water to put down, or ask me if you have trouble.

**General formulae & notation**

1 gal = 1 gallon (volume)

1 oz = 1 liquid ounce (volume)

1 ft = 1 linear foot (distance)

1 ft^2 = 1 square foot (area)

1 ft^3 = 1 cubic foot (volume)

One cubic foot is 7.48 gallons

One gallon is 1/7.48 = 0.134 ft^3

One gallon is 128 ounces

One foot is 12 inches

**Rainfall equivalent to one gallon**

One gallon x (1 cu ft / 7.48 gal) = .134 ft^3

.134 ft^3 / 1 ft^2 = .134 ft

.134 ft x (12 in / 1 ft) = 1.6 in

**so one gallon of water applied to one square foot is equivalent to 1.6 inches of rain**

**Gallon equivalent to one inch of rain**

1-in x (1-ft / 12-in) x 1 ft^2 = 1/12 ft^3 of water

1/12 ft^3 x (7.48-gal / ft^3) = 7.48/12 = .62 gal

.62 gal x (128-oz / 1 gal) = 80 oz

**so one inch of rain over one square foot is equivalent to 5/8 gallon or 80 ounces**

A free tomato to anyone who helps me correct my math.