About

About us

Cylinder Volume Calculator is a free tool for one job done properly: turning the dimensions of a cylinder into an accurate volume, in whatever unit you need.

We built it because most volume calculators stop at a single number. People measuring a real tank want gallons and litres, want to know whether a gallon is US or Imperial, and often want the formula and steps so they can trust the answer or reproduce it by hand. Every page here is organised around a specific question, with the calculator on the first screen and a clear explanation below it.

How the numbers are calculated

All results come from standard geometry: the volume of a right circular cylinder is π r² h, hollow cylinders subtract the bore, half cylinders take half, and tanks on their side use the circular-segment area. Unit conversions use exact factors — for example one US gallon is 231 cubic inches and one litre is 1000 cubic centimetres.

What we do not do

We do not ask you to sign in, and calculations run entirely in your browser. We are careful to point out the limits of a geometric figure: it does not know about wall thickness, fittings or the headspace you leave in a real tank, so we flag that wherever capacity is involved.

Spotted something that could be clearer or more accurate? Tell us.