Hollow tube & pipe

Cylindrical Pipe Volume Formula

Outer wall minus the bore: get the material volume of a pipe or the liquid it can hold, from outer and inner diameters.

This cylindrical pipe volume formula keeps two very different numbers apart: the solid material in a pipe wall, and the space inside the bore. Enter outer and inner diameters plus length, and you get each one clearly labelled.

A pipe is really two cylinders — the outside and the hole — and almost every practical question is about the difference between them. Whether you are costing the metal, sizing the flow, or estimating a coating, you are working with either the wall or the bore, and it pays to be clear which.

How the volume is worked out

The volume of a hollow cylinder is:

V = π h (R² − r²)

A worked example

Worked example. Take a cylinder with a diameter of 20 cm (so a radius of 10 cm) and a height of 40 cm. The base area is π × 10² = 314.16 cm², and multiplying by the height gives a volume of about 12.57 litres (12,566 cm³ · 3.32 US gallons).

Keep the two results apart: the wall (material) volume is the metal or plastic itself, while the bore capacity is what the pipe can carry. They are not interchangeable.

Conversions use standard factors: 1 US gallon = 231 in³, 1 Imperial gallon = 4.54609 L, 1 litre = 1000 cm³.

Using the calculator

Measure the outer diameter and the inner (bore) diameter.
Halve each to get the outer radius R and inner radius r.
Find the ring area: π (R² − r²).
Multiply by the length to get the wall (material) volume.
Read the bore capacity and material volume separately.

Getting an accurate measurement

Confirm the inner diameter is the bore, not the wall thickness. Keep every measurement in the same system, and let the tool convert between units for you.

Once the result is in

To save you a second search, here are the related answers people most often want straight after this calculation:

What is the wall thickness from the diameters?

Wall thickness is the outer diameter minus the inner diameter, divided by two. Enter both diameters and the tool uses them to separate metal from bore automatically.

What if it is a very thin tube?

The same formula applies however thin the wall — the material volume simply becomes small next to the bore, which the breakdown makes clear at a glance.

How much can the pipe carry?

The bore capacity — the space inside — is listed separately from the wall material in the result, so you can read both from a single calculation.

How do I get the weight of the pipe?

Use the wall (material) volume, not the bore, and multiply by the material density. Tick estimate weight and the tool does it once you enter a density.

Common mistakes to avoid

The classic error is mixing up the inner diameter with the wall thickness — they are not the same, and swapping them changes the answer completely. It also matters which figure you carry forward: use the wall volume for weight and material, and the bore volume for flow or capacity. The tool keeps them separate so you can pick correctly.

One result, every unit

One number, many units. Whatever you enter, the result lists the same volume as litres, US gallons, Imperial gallons, millilitres, cubic centimetres, cubic inches, cubic feet, cubic yards and cubic metres at the same time. You almost never have to convert by hand: read the figure in the unit your job uses and copy any of the others straight from the breakdown. If you need a shareable version, the copy-link button preserves your exact inputs so a colleague opens the page with the same calculation already filled in.

Keep going

Once you have your answer you may also want to work in volume formula tank capacity solid rod & bar. These related calculators pick up where this one leaves off:

Volume Tube Calculator Hollow Cylinder Volume How to Calculate Volume of a Tube Volume of Hollow Cylinder Calculator Calculate Volume of a Hollow Cylinder Volume of a Tube Calculator

When this comes in handy

People reach for this in a range of situations:

Estimating the steel in a run of pipe
Working out how much a tube can carry
Costing anti-corrosion coating from surface and volume
Comparing wall thickness options

The bottom line: with the radius or diameter and the height, the volume follows immediately, and the breakdown lets you hand the same number to anyone in the unit they prefer. Measure inside dimensions for anything that holds liquid, leave a little headspace at the top of a real container, and treat the geometric figure as a clean maximum rather than the final word on usable capacity.

Frequently asked questions

Does this work for a tank or a pipe?

Yes. A solid tank uses the standard mode; for a pipe or tube use the hollow mode, which subtracts the bore. For a tank on its side, use the horizontal mode.

How do I find the volume of a hollow cylinder?

Subtract the inner cylinder from the outer one: 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.

What is the difference between material volume and capacity?

Material volume is the solid in the wall; capacity is the empty space in the bore. A pipe's coating budget uses material volume; what it carries uses the bore capacity.

Must the inner diameter be smaller than the outer?

Yes — the bore has to fit inside the wall. The calculator will flag it if the inner value is not smaller.

What is the formula for the volume of a cylinder?

The volume is 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?

Either — just tell the calculator which you are entering. The radius is from the centre to the edge; the diameter is the full width across. The tool converts diameter to radius automatically.