What is the formula for the density of a cylinder?

Density equals mass divided by volume (rho = m / V). For a cylinder, the volume is V = pi x r^2 x h, where r is the radius and h is the height. So density = m / (pi x r^2 x h). Make sure your mass and volume units are consistent (for example, grams and cubic centimetres, or kilograms and cubic metres) before dividing.

How do I find the volume of a cylinder from its diameter?

If you know the diameter instead of the radius, divide the diameter by 2 to get the radius, then use V = pi x r^2 x h. For example, a cylinder with a 10 cm diameter and 20 cm height has a radius of 5 cm, giving a volume of pi x 5^2 x 20 = 1,570.8 cubic centimetres.

What units should I use for density?

Density is most commonly expressed in kilograms per cubic metre (kg/m3) for engineering and scientific use, or grams per cubic centimetre (g/cm3) for smaller lab samples. Water has a density of 1,000 kg/m3 (1 g/cm3), which is a useful benchmark: materials denser than water sink in it, and materials less dense float.

Density of a Cylinder Calculator

This calculator works out the density of a cylindrical object by combining its volume with its mass, so you can identify what a material might be, check whether it will float or sink, or verify a calculation for a materials science or engineering assignment. You enter the cylinder's radius (or diameter, if that is easier to measure), its height or length, and its mass, then choose your length unit (millimetres, centimetres or metres) and mass unit (grams or kilograms). The calculator first finds the volume using V = pi x r^2 x h, then divides your mass by that volume to return density in both kilograms per cubic metre and grams per cubic centimetre, alongside the volume itself in cubic centimetres and cubic metres. A working panel shows the radius and height used, the volume formula and result, and your mass, so you can follow every step of the calculation rather than just seeing an answer. It also compares your result against the density of water, 1,000 kg/m3, telling you straight away whether the object would float or sink, which is a handy sanity check if you already know the material. Because density calculations are only as accurate as your measurements, take radius and height readings at a few points if the cylinder tapers, and make sure your length and mass units are entered correctly before relying on the result. This tool assumes a solid, uniform cylinder with no hollow sections, so for pipes, tubes or composite objects you will need to calculate the volume of each section separately and combine the results.

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Method verified Standard cylinder volume and density formulas (SI units).

1. Cylinder Dimensions

Measure by

Radius

Diameter

Height (length)

Length unit

2. Mass

Mass

Mass unit

Volume and Density

Volume

1,570.8

cm3

Volume

0.001571

Density
1,000.0
kg/m3

Density

1.000

g/cm3

Working

Radius used5.000 cm

Height used20.000 cm

Volume formulaV = π × r² × h

Volume (cm3)1,570.8 cm3

Mass1,570.80 g

Density (kg/m3)1,000.0 kg/m3

Comparison to Water

Water density1,000 kg/m3 (1 g/cm3)

Your material's density1.000 g/cm3

Would it float?No, it would sink

Summary: Enter your cylinder's dimensions and mass above.

How to Find the Density of a Cylinder

Density describes how much mass is packed into a given volume. It is calculated as density = mass / volume (rho = m / V). For a cylinder, the volume depends on the radius (or diameter) and the height, using the formula V = pi x r^2 x h. Once you know the volume, divide the mass of the object by that volume to get its density.

Step by Step

Measure the radius (half the diameter) of the circular face of the cylinder.
Measure the height (or length, if the cylinder is lying on its side).
Calculate the volume: V = pi x r^2 x h.
Weigh the object to find its mass.
Divide mass by volume to get density: density = mass / volume.

Worked Example

A cylinder has a radius of 5 cm and a height of 20 cm. Its volume is V = pi x 5^2 x 20 = 1,570.8 cm3. If the cylinder has a mass of 1,570.8 g, its density is 1,570.8 / 1,570.8 = 1.00 g/cm3, which is the same as 1,000 kg/m3, equal to the density of water.

Units Matter

Quantity	SI Unit	Common Alternative
Length (radius, height)	Metres (m)	Centimetres (cm), millimetres (mm)
Mass	Kilograms (kg)	Grams (g)
Volume	Cubic metres (m3)	Cubic centimetres (cm3), litres
Density	kg/m3	g/cm3 (1 g/cm3 = 1,000 kg/m3)

Always convert your measurements to consistent units before dividing mass by volume. Mixing units (such as mass in kilograms with volume in cubic centimetres) is the most common source of error in density calculations.

Related Calculators

Sources: Standard geometric formula for cylinder volume (V = pi r^2 h) and the physics definition of density (rho = m/V), as used in NCEA and university level maths and physics.

This calculator assumes a uniform, solid cylinder with no hollow sections or voids. For hollow cylinders or composite objects, calculate volume separately for each section.