About the Volume Calculator
This volume calculator finds how much space a solid shape takes up. Choose from a rectangular box, cube, cylinder, sphere, hemisphere, cone, rectangular pyramid, triangular prism, capsule or ellipsoid, enter the dimensions in any length unit, and it returns the volume in cubic units together with the capacity in liters, US gallons and cubic feet.
Use it for school geometry, and for real-world capacity questions: how much water a tank or aquarium holds, how much soil fills a raised bed, the volume of a storage bin, a round pool or a grain hopper, or how much concrete a column needs.
All dimensions must be in the same unit, and heights are perpendicular heights. The calculator gives the geometric volume of the shape; the usable capacity of a real container is slightly smaller because of wall thickness and the space left at the top.
With the default inputs, the volume is 320. Change any value above to recalculate instantly.
How to use the volume calculator
- 1Choose the shape that best matches your object.
- 2Select the unit you measured in.
- 3Enter the dimensions shown, all in that unit.
- 4Read the volume and its capacity in liters, gallons and cubic feet.
Formula and method
Any prism or cylinder has volume equal to its cross-section area times its length: a box is l × w × h, a cylinder is πr² × h, and a triangular prism is ½ × base × height of the triangle × its length. Pointed shapes built on the same base — cones and pyramids — hold exactly one third of the matching prism or cylinder.
A sphere holds 4/3 πr³, a hemisphere half that, and an ellipsoid generalises the sphere to 4/3 πabc with three different semi-axes. A capsule is a cylinder with a hemisphere at each end, so it adds a full sphere to the cylinder. Conversions use 1 m³ = 1,000 L, 1 US gallon = 3.785411784 L and 1 ft³ = 28.3168 L.
- l, w, h
- Length, width and height
- r
- Radius
- a
- Edge of a cube
- a, b, c (ellipsoid)
- The three semi-axes
Worked examples
Storage space 10 ft × 8 ft × 4 ft
Length × width × height = 10 × 8 × 4 = 320 ft³. Since 1 ft³ ≈ 28.32 L, that is about 9,061 liters or 2,394 US gallons.
Cylindrical water tank: radius 0.5 m, height 1.2 m
π × 0.5² × 1.2 ≈ 0.9425 m³. One cubic meter is 1,000 liters, so the tank holds about 942 L, or 249 US gallons.
Ball with a 6 inch radius
4/3 × π × 6³ ≈ 904.78 in³, which converts to about 14.83 liters or 3.92 US gallons.
Cone: radius 3 cm, height 8 cm
A cone is one third of its cylinder: ⅓ × π × 3² × 8 ≈ 75.40 cm³, or about 0.075 L (75 mL).
Frequently asked questions
How do you calculate volume?+
For shapes with a constant cross-section, multiply the cross-section area by the length or height. A box is length × width × height; a cylinder is π × radius² × height.
How many liters are in a cubic foot?+
One cubic foot is about 28.32 liters, or 7.48 US gallons. One cubic meter is exactly 1,000 liters, or about 264.2 US gallons.
Why is a cone one third of a cylinder?+
A cone’s cross-section shrinks steadily to a point, and integrating that shrinking area over the height gives exactly one third of the cylinder with the same base and height. The same is true of pyramids and prisms.
What is the difference between volume and capacity?+
Volume is the space a shape occupies, usually in cubic units; capacity is how much it can hold, usually in liters or gallons. For a thin-walled container the two are almost equal.
How do I find the volume of an irregular object?+
Break it into simple shapes and add their volumes, or measure the water it displaces: submerge it in a container and the rise in water level times the container’s base area is its volume.