Cylinder volume
Cylinder Volume Calc
Enter a radius or diameter and a height to get an instant, accurate cylinder volume in any unit — with the formula and every step shown.
A cylinder is one of the friendliest shapes to measure, and the cylinder volume calc keeps it that way. Enter what you know — radius or diameter, plus height — and read the volume in litres, gallons, cubic feet or any other unit you need.
Cylinders turn up everywhere once you start noticing them — a tin of beans, a scaffold pole, a rainwater barrel, the barrel of a pump. Because they all share the same simple geometry, one calculation covers the lot, and the only thing that really changes from job to job is the unit you read the answer in.
Using the calculator
- Measure across the circular end — the diameter or radius.
- If you measured the diameter, halve it to get the radius r.
- Square the radius and multiply by π to get the base area.
- Multiply the base area by the height h: V = π r² h.
- Convert the result into your preferred unit above.
Getting an accurate measurement
If you can only reach the top, measure the diameter across the opening and halve it. Keep every measurement in the same system, and let the tool convert between units for you.
The maths in one line
The volume of a cylinder is:
V = π r² hA 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).
For anything that holds liquid, measure the inside of the cylinder — the wall takes up space that the contents cannot.
Conversions use standard factors: 1 US gallon = 231 in³, 1 Imperial gallon = 4.54609 L, 1 litre = 1000 cm³.
What people work out next
Most jobs need one or two more things once the volume lands. The common follow-ups, with the numbers you need, are below:
What if I have the diameter, not the radius?
Toggle the base input to diameter and the tool halves it for you. There is also a circumference option for when that is all you were able to measure.
How do I find a missing dimension?
If you know the volume you need and one measurement, the reverse-solver returns the height, radius or diameter that matches it.
Can I get the weight too?
Tick estimate weight, pick a material, and the calculator multiplies volume by density to show the mass in kilograms and pounds.
What will the volume be in gallons or litres?
You do not have to choose up front. The result lists litres, US gallons, Imperial gallons, cubic feet and more together, so you can switch the main unit whenever you like.
Where people use this
It comes in handy across quite different tasks:
- Checking a geometry homework answer
- Sizing a barrel, drum or planter
- Estimating pipe or duct volume
- Planning a DIY water feature
Where people go wrong
Two things trip people up: squaring the wrong number, and forgetting that the answer is cubic. If a result looks four times too big or too small, you have probably swapped radius and diameter somewhere, so it is always worth re-reading the measurement you are least sure of. It also helps to glance at the equivalent units; if the litre and gallon figures are both off by the same factor, the input is the culprit, not the maths.
One result, every unit
Showing every unit at once is about speed and safety: you see the answer in litres, gallons and cubic feet side by side, so there is no chance of applying the wrong conversion factor. Change the output unit at the top to make any of them the headline figure, switch the precision to exact if you want the value in terms of pi, and use copy-result to paste a tidy summary wherever you need it.
Related things you might need
Once you have your answer you may also want to work in gallons litres & liters volume formula. These related calculators pick up where this one leaves off:
To sum up, the whole job is two measurements and one formula. Enter them above, pick your unit, and you have an accurate figure plus every equivalent unit beside it. Keep a copy with the copy-result button, save the shareable link if someone else needs the same numbers, and use the history panel to compare a few options without starting from scratch.
Good to know
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 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.