There are 231 cubic inches of water in a gallon.
Also one inch of water can equal several gallons of water depending on how big the acreage is that the inch of rain fell on.
For example.
One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons.
An inch of snow falling evenly on 1 acre of ground is equivalent to about 2,715 gallons of water.
A good way to convert inches of water to gallons is the following.
First, multiply the . 62 gallons of water for every inch needed (. 62 gallons x 2 inches) = 1.24 gallons for 2” of water per square foot.
How do you calculate gallons per inch in a tank?
For example, if you have a tank that is 12 inches in diameter and 20 inches high, the calculation looks like this: Divide the cubic volume in inches by 231 in order to find the number of gallons.
One US liquid gallon of fresh water weighs roughly 8.34 pounds (lb) or 3.785 kilograms (kg) at room temperature.