Hollow tube & pipe
Hollow Cylinder Volume
Outer wall minus the bore: get the material volume of a pipe or the liquid it can hold, from outer and inner diameters.
A pipe or tube is a cylinder with a hole down the middle, so its volume is the outer cylinder minus the inner one. This hollow cylinder volume asks for the outer and inner diameters and returns the wall (material) volume, the bore capacity, or both.
The reason a dedicated hollow-cylinder tool helps is that the two useful numbers pull in opposite directions: a thick wall means more material but less bore, a thin wall the reverse. Seeing both from one calculation stops you reaching for the wrong one.
The formula behind it
The volume of a hollow cylinder is:
V = π h (R² − r²)A worked example
Worked example. Take a cylinder with a diameter of 15 cm (so a radius of 7.5 cm) and a height of 30 cm. The base area is π × 7.5² = 176.71 cm², and multiplying by the height gives a volume of about 5.30 litres (5,301 cm³ · 1.40 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.
What people work out next
The figure above is usually the start, not the finish. These are the questions that tend to come next, answered here so you do not have to run another search:
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.
Getting it right
Be careful to enter the bore as a diameter, not as a thickness, and to confirm the inner value really is smaller than the outer. Then choose the right output for the job: material for weight, bore for what the pipe carries.
One result, every unit
Because volume units are where most errors creep in, the tool does the converting for you. Enter your measurements once and every common unit appears together, from millilitres up to cubic metres and across to US and Imperial gallons. Pick whichever the task calls for and lift the rest from the list; nothing needs a second calculation. The result also updates live as you change a measurement, so you can compare two sizes quickly without starting over.
Related things you might need
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:
Where people use this
A few of the jobs it gets used for:
- 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
In short: measure the width and the height, keep them in the same unit, and the tool turns them into a volume you can read in litres, gallons, cubic feet or anything else, with the working shown so you can trust it. If a result ever looks off, re-enter the measurement you are least sure of, or switch to the diameter input and let the tool halve it for you, which catches the most common error before it matters.
Good to know
Is the volume of a cylinder squared or cubed?
Does this work for a tank or a pipe?
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.What is the difference between material volume and capacity?
Must the inner diameter be smaller than the outer?
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.