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Tank Volume Calculator
Calculate the capacity of a tank in gallons and liters, and how much liquid is in it at a given depth. It handles vertical cylinders, horizontal cylinders — where a dipstick reading is not proportional to volume — and rectangular tanks.
- Liquid in the tank
- 282.01 gal
- Percent full
- 50%
- Capacity in liters
- 2,135 L
- Capacity in cubic feet
- 75.4 cu ft
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Choose the tank shape.
- Enter the inside dimensions.
- Enter the depth of liquid measured from the bottom.
- Read the total capacity, the volume of liquid and the percent full.
Worked examples
A vertical cylinder 48 in across and 72 in tall, filled to 36 in
- Capacity in cubic feet
- 75.4 cu ft
- Total capacity
- 564.02 gal
- Liquid in the tank
- 282.01 gal
- Percent full
- 50%
A horizontal cylinder 48 in across and 120 in long with 12 in of liquid
- Capacity in cubic feet
- 125.66 cu ft
- Total capacity
- 940.03 gal
- Liquid in the tank
- 183.78 gal
- Percent full
- 19.55%
A rectangular tank 48 × 24 × 24 in, full
- Capacity in cubic feet
- 16 cu ft
- Total capacity
- 119.69 gal
- Percent full
- 100%
- Capacity in liters
- 453.1 L
Horizontal tanks and dipsticks
In a cylinder lying on its side the width of the liquid surface changes with depth, so the level is not proportional to the contents. A quarter of the way up the dipstick the tank is only about 19.6% full; at half it is 50%; at three quarters it is about 80.4%.
This calculator assumes flat ends. Tanks with domed or dished heads hold a little more than shown.
Inside versus outside dimensions
Use inside measurements where you can. For thin steel or plastic tanks the wall hardly matters, but a glass aquarium or a concrete cistern can lose several percent to wall thickness. Usable capacity is also a little less than the brim-full figure, because tanks are not filled right to the top.
Questions people ask
How do I calculate the gallons in a cylindrical tank?
Multiply π × radius² × length in inches to get cubic inches, then divide by 231. A tank 48 in across and 72 in long holds 130,288 cubic inches, which is 564 gallons.
How many gallons is a 48×24×24 inch tank?
27,648 cubic inches, which is 119.7 US gallons or about 453 liters.
How full is a horizontal tank at one quarter depth?
About 19.6% full, not 25%, because the bottom of the circle is narrower than the middle.