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Cylinder Volume Calculator
Enter a radius or diameter and a height. Get the exact volume in gallons, litres, cubic feet, cubic inches and more — with the formula and every step shown.
A cylinder is any straight tube-shaped object — a can, a pipe, a water tank, a drum, a fence post. Its volume is the area of the round end multiplied by how tall it is, written V = π r² h. This cylinder volume calculator does that arithmetic for you and, just as importantly, converts the answer into whatever unit you actually need — from litres and gallons to cubic feet and cubic inches.
How to use the cylinder volume calculator
- Choose whether you are entering a radius, a diameter or a circumference.
- Type the value in and pick its unit — millimetres, centimetres, metres, inches, feet or yards.
- Enter the height (or length) of the cylinder.
- Press Calculate. The result appears with a full unit breakdown and the working underneath.
Everything runs in your browser, so nothing is uploaded and the tool keeps working even with a poor connection. On a phone, the result panel slides into view the moment you calculate.
The cylinder volume formula
For a right circular cylinder the formula is V = π r² h — the area of the circular base, π r², multiplied by the height h.
Standard V = π r² h
Hollow tube V = π h (R² − r²)
Half cylinder V = ½ π r² h
Elliptical V = π a b hIf you have the diameter instead of the radius
Halve the diameter first: r = d ÷ 2. The formula then becomes V = π (d/2)² h, which is the same as V = π d² h ÷ 4. The calculator does this step automatically when you switch to diameter mode.
The exact value in terms of π
Leaving π in the answer gives the exact form — for example 144π in³ rather than 452.39 in³. Set the precision control to “Exact” to read it that way, which is what most homework questions expect.
Worked example. Take a cylinder with a diameter of 30 in (so a radius of 15 in) and a height of 48 in. The base area is π × 15² = 706.86 in², and multiplying by the height gives a volume of about 146.9 US gallons (33,929 in³ · 556.0 litres).
Units and inputs it supports
Measure in one system and read the answer in another — the tool converts between all of them and shows every unit at once.
Length units for measurements
Millimetres (mm), centimetres (cm), metres (m), inches (in), feet (ft) and yards (yd). Each field has its own unit, so you can mix them freely.
Volume and capacity units for the result
Cubic millimetres, cubic centimetres, millilitres, litres and cubic metres; cubic inches, cubic feet and cubic yards; and liquid capacity in US gallons, Imperial gallons and US fluid ounces.
Every cylinder shape, not just the simple one
Real tanks lie on their sides, pipes are hollow, and some vessels are oval. There is a dedicated tool for each:
Where these numbers come from
The calculators use standard, internationally recognised definitions, so the results line up with official references rather than rounded shortcuts.
US and Imperial gallons
One US liquid gallon is defined as exactly 231 cubic inches (about 3.785 411 784 litres). One Imperial gallon is exactly 4.546 09 litres (about 277.42 cubic inches).
Why the two gallons differ
They come from different historical standards: the US gallon from the old English wine gallon, the Imperial gallon defined later in Britain. An Imperial gallon is roughly 20% larger, which is exactly why this tool always asks which one you mean and shows both.
Metric and other factors used
- 1 litre = 1000 cubic centimetres; 1 cubic metre = 1000 litres.
- 1 cubic foot = 1728 cubic inches ≈ 7.4805 US gallons.
- π is carried to full double precision (≈ 3.141592653589793).
Unit definitions follow NIST and international standards for US customary and metric measures.
Common tank sizes at a glance
A quick reference for upright tanks, using inside dimensions in inches:
| Diameter × Height (in) | US gallons | Litres |
|---|---|---|
| 24 × 36 | 71 | 267 |
| 30 × 48 | 147 | 556 |
| 36 × 60 | 264 | 1001 |
| 48 × 72 | 564 | 2135 |
| 60 × 96 | 1175 | 4448 |
Where this calculator gets used
- Water storage, rainwater butts and irrigation tanks on farms and in gardens
- Fuel, oil and chemical drums in industry and workshops
- Pipes, tubes and ducts — both the material and what they carry
- Kitchen and baking swaps between round tins and jars
- Geometry homework, where the steps matter as much as the answer
These are geometric gallons from the dimensions you enter. A real tank holds slightly less once wall thickness, fittings and headspace are taken into account — and always confirm whether you need US or Imperial gallons.
What people use it for
“I dip our horizontal diesel tank every week. Punching the depth in and reading the litres left has replaced a laminated chart nobody trusted.”
“Sizing rainwater butts for clients used to mean a spreadsheet. Now I show them the gallons and litres side by side in seconds.”
“My students finally understand why the answer comes out in cubic units once they can see every step laid out.”
Frequently asked questions
What is the formula for the volume of a cylinder?
V = π r² h — the area of the circular base (π r²) multiplied by the height (h). If you have the diameter instead of the radius, halve it first: r = d ÷ 2.Do I use radius or diameter?
What units can I use?
Is the volume of a cylinder squared or cubed?
Does this work for a tank or a pipe?
What is the difference between US and Imperial gallons?
How do I convert cubic inches to gallons?
How do I find how full my tank is?
Why can't I use π r² h for a horizontal tank?
How do I find the volume of a hollow cylinder?
V = π h (R² − r²), where R is the outer radius and r is the inner radius. The tool asks for diameters and does the halving for you.Browse all calculators
There is a page for almost every way people phrase this — see the full list of calculators, read the guides, or start with the gallons, litres and formula pages.