Volume Calculator
Choose a shape, enter its dimensions in meters or feet, and get the volume in cubic meters, cubic feet, liters and US gallons — plus the surface area, with the formula written out in your numbers.
Formula and calculation
Worked example
A box 2 m long, 1.5 m wide and 1 m high holds 3 cubic meters — the same as 3,000 liters or 792.5162 US gallons — and its surface area is 13 square meters.
Which volume unit should you use?
Cubic meters suit rooms, excavation and anything you would measure with a tape in metric. Liters are for liquids and containers, and 1 m³ is exactly 1,000 of them. Cubic feet dominate in the United States for shipping, appliances and HVAC, and 1 m³ is 35.31 ft³. Gallons are for fuel and US retail liquids — but check which gallon: a US gallon is 3.785 liters while an imperial gallon is 4.546, a 20% difference that has caused real disputes. This page reports all four so you never have to convert in your head.
Why a cone or pyramid is one third
A cylinder, a cone, a prism and a pyramid all start from “base area × height”. The cone and pyramid carry an extra ÷ 3 because they taper: three cones of the same base and height fill their cylinder exactly, a fact you can demonstrate by pouring. That is the whole reason the formula reads π r² h ÷ 3 rather than something less tidy. The same relationship holds at any size — a pyramid twice as tall and twice as wide on each side holds eight times the volume, which is why scale models and shipping containers surprise people.
What the results mean
- Volume
- The space the solid occupies, in cubic meters — the primary result. One cubic meter is 1,000 liters or about 264 US gallons.
- Volume in cubic feet
- The same volume in cubic feet, the unit used for shipping, freight and appliance sizes in the United States. 1 m³ is 35.31 ft³.
- Volume in liters
- The same volume in liters — the metric unit for liquids and for container and tank sizes.
- Volume in US gallons
- The same volume in US gallons (1 US gallon = 3.785 liters). Note that an imperial gallon is larger, 4.546 liters.
- Surface area
- The total area of the outer surface in square meters: every face, including both ends of a cylinder and the base and curved side of a cone.
- Surface area in square feet
- The same surface area in square feet — handy when you are pricing paint, wrapping or sheet material in US units.
- Calculation
- The volume formula for the shape you picked, with your numbers substituted in, so you can check the arithmetic line by line.
Frequently asked questions
How do I calculate the volume of a box?
Multiply length by width by height, in matching units. A box 2 m by 1.5 m by 1 m is 2 × 1.5 × 1 = 3 cubic meters, which is 3,000 liters. If you measure in feet, the answer comes out in cubic feet — 1 m³ is 35.31 ft³.
How many liters are in a cubic meter?
Exactly 1,000 — a liter is defined as one cubic decimeter, so the conversion is a clean factor of 1,000. That same cubic meter is 264.17 US gallons or 35.31 cubic feet. This is the conversion most people need for a tank, a pool or a rainwater butt.
Why is the volume of a cone one third of a cylinder's?
Because they share the same base and height. Fill a cone with water and pour it into a matching cylinder three times and the cylinder is full — so the cone is π r² h ÷ 3 and the cylinder is π r² h. The pyramid behaves the same way against a prism.
Does the pyramid calculation work for any pyramid?
No — it assumes a regular pyramid with a square base and a straight, vertical height. Pyramids with rectangular, triangular or irregular bases need their own base area, and a slanted or oblique pyramid needs the true perpendicular height rather than a measured edge.