Cylinder Volume Without Radius
No radius? No problem. If you have the diameter, circumference, base area, or surface area, this calculator derives the radius and computes the volume. Most real-world measurements give one of these alternatives rather than the radius directly.
Volume Without Radius
Getting the Radius from Other Values
From diameter: r = d / 2
From circumference: r = C / (2π)
From base area: r = √(A / π)
From total surface area (with known h): SA = 2πr² + 2πrh 2πr² + 2πhr − SA = 0 r = [−2πh + √(4π²h² + 8πSA)] / (4π)
Once you have r, volume is V = πr²h.
Most Common: Using Diameter
In most practical situations, you have the diameter — from a label, spec sheet, or direct measurement. The conversion is simple: divide by 2.
V = π × (d/2)² × h = (π × d² × h) / 4
This is the same formula as V = πr²h, just written in terms of d. Many online calculators accept diameter directly for convenience.
Remember: pipe sizes, bolt sizes, and drill bits are specified by diameter, not radius.
Using Circumference
When measuring round objects in the field, a tape measure around the outside gives the circumference. This is common for trees, tanks, pipes, and columns.
r = C / (2π), then V = πr²h = C²h / (4π)
Example: A column with circumference 157 cm and height 300 cm. r = 157 / 6.2832 = 24.99 cm. V = π × 624.5 × 300 = 588,732 cm³ ≈ 588.7 litres.
This method is especially useful when you can't access the inside of the cylinder to measure a diameter.