Calculate the mass or weight of a solid or hollow cylinder from its diameter and length, using typical material densities or your own density.
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Cylinder Mass Formula
Mass equals volume times density. The volume formula changes with the shape.
Solid cylinder:
Hollow tube:
Known volume:
- m = mass (kg)
- r = inner radius for a tube, or radius for a solid cylinder (m)
- R = outer radius of a tube (m)
- L = length or height (m)
- V = total volume (m³)
- rho = density of the material (kg/m³)
Assumptions: the cross section is a perfect circle, the wall thickness of a tube is uniform, and the material density is constant. If you enter a diameter, the calculator divides by two before squaring. All inputs are converted to SI units before the math runs, then the result is reported in kg, lb, metric tons, and short tons.
The calculator solves for mass, density, length or outer diameter from measured diameters. Hollow tubes subtract the bore from the outer cross section. The known-volume mass mode skips geometry and uses the supplied material volume.
Reference Tables
Illustrative density assumptions, not certified values. Verify actual material grade, moisture and temperature before use:
| Material | kg/m³ | lb/ft³ | lb/in³ |
|---|---|---|---|
| Steel / iron | 7850 | 490 | 0.284 |
| Stainless 304 | 8000 | 499 | 0.289 |
| Aluminum | 2700 | 169 | 0.098 |
| Copper | 8960 | 559 | 0.324 |
| Brass | 8500 | 531 | 0.307 |
| Concrete | 2400 | 150 | 0.087 |
| Plastic (PE) | 950 | 59 | 0.034 |
| Wood (avg) | 600 | 37 | 0.022 |
| Water | 1000 | 62.4 | 0.036 |
Quick mass per meter for a steel solid round bar (rho = 7850 kg/m³):
| Diameter | kg per meter | lb per foot |
|---|---|---|
| 10 mm | 0.62 | 0.41 |
| 20 mm | 2.47 | 1.66 |
| 25 mm | 3.85 | 2.59 |
| 40 mm | 9.86 | 6.63 |
| 50 mm | 15.41 | 10.36 |
| 75 mm | 34.68 | 23.30 |
| 100 mm | 61.65 | 41.43 |
Worked Examples and FAQ
Example 1: Solid steel shaft. Diameter 50 mm, length 2 m, steel at 7850 kg/m³.
Radius = 0.025 m. Volume = pi × 0.025² × 2 = 0.003927 m³. Mass = 0.003927 × 7850 = 30.83 kg.
Example 2: Aluminum tube. Outer diameter 4 in, inner diameter 3.5 in, length 24 in, aluminum at 2700 kg/m³.
Outer radius = 0.0508 m, inner radius = 0.04445 m, length = 0.6096 m. Volume = pi × (0.0508² – 0.04445²) × 0.6096 = 0.001158333 m³. Mass = 0.001158333 × 2700 = 3.127500 kg, or 6.894957 lb.
Example 3: Concrete column from a known volume. Volume = 1.2 m³, density = 2400 kg/m³.
Mass = 1.2 × 2400 = 2880 kg.
Does the orientation of the cylinder matter? No. Mass depends only on volume and density.
What if my material is not in the list? Enter its verified density directly. Editable suggestions show illustrative values; the entered density is used.
Can I use this for liquids in a tank? For an upright tank, use its inside diameter and liquid fill height, with a density verified for the actual liquid and temperature. A horizontal partially filled tank needs a different volume model.
Why does my tube weight not match a supplier chart? Suppliers often use nominal pipe sizes where the listed diameter is not the actual outer diameter. Use actual outer and inner dimensions and a verified density; tolerances, coatings and end caps may also affect mass.
How do I convert g/cm³ to kg/m³? Multiply by 1000. So 7.85 g/cm³ equals 7850 kg/m³.
