# Tank Volume Calculator for Rectangular and Cylindrical Shape

Estimate the fill capacity of common tank shapes with our easy-to-use calculator. We’ll also provide you with manual calculations to determine the number of US gallons your tank will hold.

## Tank Volume Calculator for rectangular and cylinder shape.

Select the tank shape and enter the dimensions in feet to calculate the tank volume and number of US gallons:

To find the total tank volume for a rectangular tank, enter the tank’s length, width, and depth in feet. The calculator will automatically compute the volume in cubic feet and the number of US gallons your tank will hold.

Tank volume in cubic feet = length (ft) x height (ft) x depth (ft)

Note: If your dimensions are in inches, divide the number of inches by 12 to convert to feet. For example, if your tank has a length of 44 inches, 44/12 equals 3.67 feet.

The formula to compute volume for a cylindrical tank is different. You’ll need to know the tank’s radius, which is the diameter divided by two. You’ll also need the height for a vertical cylinder or length for a horizontal cylinder.

Vertical cylindrical tank volume in cubic feet = 3.14 x radius (ft) x radius (ft) x height (ft)

Horizontal cylindrical tank volume in cubic feet = 3.14 x radius (ft) x radius (ft) x length (ft)

Since there are about 7.5 gallons in one cubic foot, you can convert volume to gallons by multiplying by 7.5.

US Gallons = Cubic Footage x 7.5

## Examples of How to Calculate Tank Volume

In our first example, we’ll calculate the volume of a rectangular tank with the dimensions 3’ x 2’ x 2.5’.

• To find the volume in cubic feet, we’ll multiply length x width x depth
• Cubic feet = 3 x 2 x 2.5
• Cubic feet = 15
• To determine the number of gallons our tank will hold, we’ll multiply cubic feet by 7.5
• US Gallons = 15 x 7.5
• US Gallons = 112.5

In our second example, we’ll compute the volume of a vertical cylindrical tank with a 6’ diameter and 4’ height.

• To find the volume in cubic feet, multiply the pi x the radius x radius x height.
• Our radius is 3’, which is half of our diameter. We’ll use 3.14 to represent pi.
• Cubic feet = 3.14 x 3 x 3 x 4
• Cubic feet = 113.04
• To determine gallon capacity, multiply cu ft by 7.5.
• US Gallons = 113.04 x 7.5
• US Gallons = 847.8

## How to Calculate the Filled Volume of a Tank

If your tank is partially filled, and you want to know how many gallons it’s holding, use one of these formulas, ensuring all measurements are in feet.

Filled volume for a rectangular tank:

Volume = length x width x filled depth

Multiply the volume total by 7.5 to determine how many gallons your tank currently holds.

Filled volumed for a vertical cylindrical tank:

Multiply the volume total by 7.5 to determine the number of US gallons in the tank.