How to Calculate Gallons and Tank Volume

How to Calculate Gallons and Tank Volume
••• AnjanSapkota/iStock/GettyImages

If you don't know how many gallons a tank can hold, you can calculate it yourself using a simple formula. The measurements you need to calculate the volume are different, depending on the tank you have. Rectangular tanks, like aquariums require one formula, while cylindrical tanks, like drinking water tanks, require another.

Rectangular Tanks

Measure the length, width and depth of the tank using a tape measure. You can measure from the inside of the tank or, if preferable, measure the outside and then subtract the width of the tank walls to determine the inside measurement.

Next, multiply the length, width and depth measurements in order to find the cubic volume in cubic inches. For example, if the measurements are 20 inches by 12 inches by 12 inches, the volume is 2,880 cubic inches.

Finally, divide the cubic volume in inches by 231, as a gallon is equal to 231 cubic inches. A 2,880 cubic-inch tank is 12.47 gallons

Cylindrical Tanks

Measure the height and radius of the tank. The radius is the distance from the center of the tank to its outer edge. Another way to find the radius is to divide the diameter, or width, by two.

Square the radius by multiplying the radius times itself and then multiply it by 3.1416, which is the constant pi. Multiply this number by the height to determine the cubic volume in inches. 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.

Tips

  • If you want to measure larger tanks in feet, multiply the cubic feet by 7.48 to convert cubic feet to gallons. The precise conversion factor is 7.48052.

Related Articles

How to Convert Inches to Gallons for an Oil Tank
How to Calculate the Capacity of a Cylinder
How to Find the Volume of a Sphere in Terms of Pi
How to Calculate the Diameter of a Circle From a Linear...
How to Convert Inches to Gallons for an Oil Tank
How to Calculate Tank Size
How Do I Calculate the Capacity of a Filing Cabinet?
How to Calculate Hydraulic Cylinder Tonnage
How to Calculate the Volume of a Cylinder in Ounces
How to Calculate Gallons by Cubic Feet
How to Calculate Outside Diameter
How to Calculate the Volume and Circumference of a...
How to Calculate Volume of a Circular Cylinder
How to Find the Volume of a Triangular Pyramid
How to Calculate the Volume of a Pipe
How to Calculate Cubic Feet of a Cylinder
How to Calculate the Perimeter of Quadrilaterals
How to Calculate Circumference in Inches
How to Convert Diameter to Square Centimeters
How to Calculate Perimeter and Area Ratio

Dont Go!

We Have More Great Sciencing Articles!