Work out the volume of a cube, box, cylinder, cone, sphere or pyramid — pick the shape, enter its measurements, and the calculator shows the volume in cubic units with the formula and the numbers worked out. It runs entirely in your browser: free, instant, no sign-in.
How the volume calculator works
Volume is the amount of space inside a three-dimensional shape, measured in cubic units — cubic centimetres (cm³), cubic metres (m³), cubic inches (in³) and so on. Pick the shape, enter its measurements in the same unit, and the calculator applies that shape’s formula: a cube is side × side × side, a rectangular prism is length × width × height, a cylinder is π × radius² × height, a cone is a third of the cylinder with the same base and height, a sphere is ⁴⁄₃ × π × radius³, and a square pyramid is a third of the base area times the height. The result updates as you type, and the calculator shows the numbers substituted into the formula so you can check the working.
Volume is the amount of space inside a three-dimensional shape — how much water a tank holds, how much soil fills a planter, or how much air fits in a ball. The Volume Calculator works it out for six common shapes: cube, rectangular prism, cylinder, cone, sphere and square pyramid. Pick the shape, enter its measurements, and the calculator shows the volume in cubic units, with the formula and the substituted numbers so you can check the working. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and there is no sign-in and no limit on how often you use it.
Every measurement you enter must use the same unit — all centimetres, all metres, all inches — and the answer comes out in that unit cubed: cubic centimetres (cm³), cubic metres (m³), cubic inches (in³). Mix the units and the answer is meaningless, so measure everything the same way first.
How to use the calculator, step by step
The calculator has one job per shape, and it only ever shows the inputs that shape needs.
- Step 1 — Pick the shape. Tap one of the six shape buttons: Cube, Rectangular prism, Cylinder, Cone, Sphere or Square pyramid. Only that shape’s measurements appear.
- Step 2 — Enter the measurements. Type each measurement in the same unit. A cube needs only its side length; a cylinder and a cone need a radius and a height; a sphere needs only its radius; a rectangular prism needs a length, width and height; a square pyramid needs its base side and height. Decimals are fine — 2.5 works the same as 2 or 3.
- Step 3 — Read the result. The volume appears straight away, rounded to two decimal places, with the formula and your numbers substituted in — for example, π × 3² × 5 = 141.37 for a cylinder with radius 3 and height 5. If a box is empty, zero or negative, the calculator says so plainly instead of showing a wrong number.
- Step 4 — Start again with Clear. The Clear button empties the current shape’s inputs so you can measure the next shape. Switching shapes keeps the other shapes’ inputs untouched.
The formulas
Each shape has its own volume formula. The calculator applies the right one for the shape you pick:
- Cube volume: V = s³. Multiply the side length by itself three times. A cube with side 4 has volume 4 × 4 × 4 = 64 cubic units.
- Rectangular prism volume: V = l × w × h. Multiply length × width × height. A box 2 × 3 × 4 has volume 2 × 3 × 4 = 24 cubic units.
- Cylinder volume: V = πr²h. Multiply π (3.14159…) by the radius squared, then by the height. A cylinder with radius 3 and height 5 has volume π × 3² × 5 = π × 9 × 5 = 141.37 cubic units.
- Cone volume: V = ⅓πr²h. A cone holds exactly one third of the cylinder with the same base and height. A cone with radius 3 and height 6 has volume ⅓ × π × 3² × 6 = ⅓ × π × 9 × 6 = 56.55 cubic units.
- Sphere volume: V = ⁴⁄₃πr³. Multiply ⁴⁄₃ by π, then by the radius cubed. A sphere with radius 2 has volume ⁴⁄₃ × π × 2³ = ⁴⁄₃ × π × 8 = 33.51 cubic units.
- Square pyramid volume: V = ⅓s²h. Multiply the base side squared by the height, then take a third. A pyramid with base side 4 and height 6 has volume ⅓ × 4² × 6 = ⅓ × 16 × 6 = 32 cubic units.
The two “one third” formulas are worth remembering together: a cone is one third of its cylinder, and a square pyramid is one third of the box that would enclose it. That is why a cone and a pyramid with the same base and height as a cylinder and a box hold a third of the volume.
Worked examples
Example 1 — cylinder volume, radius 3, height 5. Square the radius: 3² = 9. Multiply by the height: 9 × 5 = 45. Multiply by π: 45 × 3.14159… = 141.37 cubic units. This is the volume of a tank, pipe or drum with those measurements.
Example 2 — cube volume, side 4. Multiply the side by itself three times: 4 × 4 × 4 = 64 cubic units. A cube with side 10 holds 10 × 10 × 10 = 1,000 cubic units — which is why a 10 cm cube holds exactly 1 litre.
Example 3 — sphere volume, radius 2. Cube the radius: 2³ = 8. Multiply by π: 8 × 3.14159… = 25.13. Multiply by ⁴⁄₃: 25.13 × 1.3333… = 33.51 cubic units. Double the radius to 4 and the volume grows eight times, to 268.08 cubic units — volume grows with the cube of the radius, not in proportion to it.
Example 4 — cone volume, radius 3, height 6. Square the radius: 3² = 9. Multiply by the height: 9 × 6 = 54. Multiply by π: 54 × 3.14159… = 169.65. Take a third: 169.65 ÷ 3 = 56.55 cubic units. The cylinder with the same radius and height would hold 169.65 — exactly three times as much.
Example 5 — rectangular prism volume, 2 × 3 × 4. Multiply the three sides: 2 × 3 = 6, then 6 × 4 = 24 cubic units. Order does not matter — length × width × height gives the same answer whichever side you call the length.
Example 6 — square pyramid volume, base side 4, height 6. Square the base side: 4² = 16 — that is the area of the square base. Multiply by the height: 16 × 6 = 96. Take a third: 96 ÷ 3 = 32 cubic units.
Common mistakes
- Using the diameter instead of the radius. The cylinder, cone and sphere formulas need the radius — half the diameter. A cylinder 6 across has radius 3, not 6. Using the diameter doubles the radius, and because the radius is squared, the answer comes out four times too big.
- Forgetting to square or cube. Cylinder volume needs r² and sphere volume needs r³, not just r. A sphere with radius 2 is ⁴⁄₃ × π × 8 = 33.51, not ⁴⁄₃ × π × 2 = 8.38.
- Forgetting the ⅓ in the cone and pyramid. A cone is not πr²h — that is the cylinder. The cone is a third of that: ⅓πr²h. The same goes for the square pyramid: ⅓s²h, not s²h.
- Mixing units. A length in centimetres and a height in metres cannot go into the same formula. Convert everything to one unit first — 1 metre is 100 centimetres — or the answer is wrong by a factor of 100, 10,000 or 1,000,000 depending on how many measurements were mixed.
- Confusing volume with surface area. Volume is the space inside, measured in cubic units (cm³); surface area is the skin outside, measured in square units (cm²). A cube with side 4 has volume 64 cm³ but surface area 6 × 16 = 96 cm² — two different numbers for two different questions.
Related tools
The volume calculator sits in the Math group, and these companion tools cover the rest of a measuring and calculating workflow.
- Percentage Calculator — work out percentages, percentage increases and decreases, and what a number is as a percentage of another.
- Word Counter — count the words and characters in any text, for essays, reports and captions.
- Currency Converter — convert between currencies at live exchange rates when a project spans two countries.
- Gold Value Calculator — work out the metal value of gold from its weight and karat at the live price.
For all of ToolZana’s free tools, start at the ToolZana home page.
Tips for measuring volume in real life
- Measure the inside, not the outside. For a tank or container, the volume that matters is the inside space — subtract the wall thickness, or measure the interior directly.
- Measure the radius across the middle. For a cylinder or a ball, measure straight across the widest point and halve it. Measuring near an edge gives a smaller diameter and a smaller answer.
- For a pyramid, height means vertical height. Use the straight vertical distance from the base to the tip, not the slanted edge running up the side — the slanted edge is always longer and would inflate the answer.
- Round only at the end. The calculator shows two decimal places, but keep full precision while you work — rounding the radius early and then squaring it doubles the rounding error.
- Sanity-check with a box. Any shape fits inside a box: a sphere of radius 2 fits in a 4 × 4 × 4 box of volume 64, so a sphere answer above 64 for radius 2 is impossible. The real answer, 33.51, is a little over half the box — which is right for a sphere.
The short version
The Volume Calculator works out the volume of six shapes in cubic units: cube volume is s³ (side 4 → 64), rectangular prism volume is l × w × h (2 × 3 × 4 → 24), cylinder volume is πr²h (radius 3, height 5 → 141.37), cone volume is ⅓πr²h (radius 3, height 6 → 56.55), sphere volume is ⁴⁄₃πr³ (radius 2 → 33.51), and square pyramid volume is ⅓s²h (base 4, height 6 → 32). Enter all measurements in the same unit, use the radius — not the diameter — for round shapes, and remember the ⅓ in the cone and pyramid formulas. The tool is free, runs entirely in your browser, and needs no sign-in.
Frequently Asked Questions
What is a volume calculator?
A volume calculator works out how much space is inside a three-dimensional shape, in cubic units. Pick the shape — cube, rectangular prism, cylinder, cone, sphere or square pyramid — enter its measurements, and it applies the right formula and shows the volume with the working. It answers questions like how much water a tank holds, how much soil fills a planter, or how much concrete a footing needs.
How do I use the volume calculator?
Pick one of the six shapes, then type its measurements into the boxes that appear — a cube needs only its side length, a sphere only its radius, a cylinder and a cone need a radius and a height, a rectangular prism needs a length, width and height, and a square pyramid needs its base side and height. The volume appears straight away, rounded to two decimal places, with the formula and your numbers substituted in. Enter every measurement in the same unit, and use the Clear button to start a new calculation.
How do I calculate the volume of a cylinder?
The cylinder volume formula is V = πr²h: multiply π (3.14159…) by the radius squared, then by the height. For a cylinder with radius 3 and height 5, that is π × 3² × 5 = π × 9 × 5 = 141.37 cubic units. Remember to use the radius — half the diameter — and to square it: a cylinder 6 across has radius 3, so r² is 9, not 36.
How do I calculate the volume of a sphere?
The sphere volume formula is V = ⁴⁄₃πr³: multiply ⁴⁄₃ by π, then by the radius cubed. For a sphere with radius 2, that is ⁴⁄₃ × π × 2³ = ⁴⁄₃ × π × 8 = 33.51 cubic units. Volume grows with the cube of the radius, so doubling the radius makes the volume eight times bigger — a sphere with radius 4 holds 268.08 cubic units.
How do I calculate the volume of a cone?
The cone volume formula is V = ⅓πr²h: square the radius, multiply by the height and by π, then take a third. For a cone with radius 3 and height 6, that is ⅓ × π × 3² × 6 = ⅓ × π × 9 × 6 = 56.55 cubic units. A cone holds exactly one third of the cylinder with the same base and height — that cylinder would hold 169.65 cubic units.
How do I calculate the volume of a cube?
The cube volume formula is V = s³: multiply the side length by itself three times. A cube with side 4 has volume 4 × 4 × 4 = 64 cubic units, and a cube with side 10 has volume 10 × 10 × 10 = 1,000 cubic units. Because every edge of a cube is the same length, the side is the only measurement you need.
How do I calculate the volume of a rectangular prism?
The rectangular prism volume formula is V = l × w × h: multiply the length, width and height together. A box measuring 2 × 3 × 4 has volume 2 × 3 × 4 = 24 cubic units. The order does not matter — length × width × height gives the same answer whichever side you call the length — but all three measurements must use the same unit.
How do I calculate the volume of a square pyramid?
The square pyramid volume formula is V = ⅓s²h, where s is the side of the square base and h is the vertical height. For a pyramid with base side 4 and height 6, that is ⅓ × 4² × 6 = ⅓ × 16 × 6 = 32 cubic units. Use the straight vertical height from the base to the tip, not the slanted edge up the side — the slanted edge is longer and would inflate the answer. A pyramid holds one third of the box that would enclose it.
What units does the volume calculator use?
The calculator works in whatever unit you enter — centimetres, metres, inches, feet — and gives the answer in that unit cubed: cm³, m³, in³ or ft³. The only rule is that every measurement for one shape must use the same unit. Enter a length in centimetres and a height in metres and the answer is wrong, so convert first: 1 metre is 100 centimetres, and 1 foot is 12 inches.
What is the difference between volume and surface area?
Volume is the space inside a shape, measured in cubic units (cm³) — how much it holds. Surface area is the skin outside, measured in square units (cm²) — how much material covers it. A cube with side 4 has volume 4 × 4 × 4 = 64 cm³ but surface area 6 × 16 = 96 cm². They answer different questions: volume for filling, surface area for covering or painting.
Can I use decimals or fractions in the calculator?
Yes — decimals work exactly like whole numbers: a cylinder with radius 2.5 and height 4 has volume π × 2.5² × 4 = 78.54 cubic units. For a fraction, type its decimal equivalent: ½ is 0.5, ¾ is 0.75, and ⅓ is 0.333. The calculator shows the result rounded to two decimal places, but it keeps full precision while working, so rounding only happens at the end.
Is the volume calculator free?
Yes — the Volume Calculator is completely free, with no sign-in and no limits. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and you can use it as often as you like, for any of the six shapes, with any measurements.