Capacity Calculator
Work out the capacity of a tank or container from its dimensions. Pick a shape, enter the measurements in any unit, and read the volume in liters, gallons, cubic feet, and more — handy for water tanks, aquariums, fuel tanks, pools, and storage containers.
Rectangular · V = length × width × height
Capacity formulas by shape
| Shape | Volume formula |
|---|---|
| Rectangular tank / box | V = length × width × height |
| Vertical cylinder | V = π × (diameter ÷ 2)² × height |
| Horizontal cylinder (full) | V = π × (diameter ÷ 2)² × length |
| Cone | V = ⅓ × π × (diameter ÷ 2)² × height |
| Sphere | V = 4⁄3 × π × (diameter ÷ 2)³ |
| Capsule | V = π·r²·L + 4⁄3·π·r³ |
A rectangular tank 2 m long, 1 m wide, and 1 m deep holds 2 × 1 × 1 = 2 m³, which is 2,000 liters (about 528 US gallons).
Measure to the inside walls of the container for true capacity, and keep every dimension in the same unit. The calculator converts the final volume into liters, gallons, and cubic units for you.
Frequently asked questions
How do I calculate the capacity of a tank?+
Measure the tank’s dimensions, choose the matching shape, and apply its volume formula. For a rectangular tank, multiply length × width × height. For a cylindrical tank, use π × radius² × height. This calculator does the math and converts the result into liters, gallons, and other units automatically.
What is the formula for the volume of a cylinder tank?+
The volume of a cylinder is π × (diameter ÷ 2)² × height (or length, for a horizontal cylinder). For example, a cylinder 1 m across and 2 m tall holds π × 0.5² × 2 ≈ 1.571 cubic meters, which is about 1,571 liters.
How many liters are in 1 cubic meter?+
1 cubic meter equals exactly 1,000 liters. It also equals about 264.17 US gallons or 219.97 imperial gallons.
How do I convert tank capacity to gallons?+
Multiply the volume in cubic meters by 264.17 for US gallons, or by 219.97 for imperial (UK) gallons. This calculator shows both automatically alongside liters and cubic feet.
Does this calculate a partially filled tank?+
No — it computes the full (maximum) capacity of each shape. For a horizontal cylinder, partial-fill volume depends on the liquid depth and requires a separate calculation.