Calculate the weight of a tube in kg or lb from its outer diameter, inner diameter or wall thickness, length and material, using typical densities.
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Weight of Tube Formula
The theoretical mass of a tube equals tube-wall volume multiplied by material density. The calculator converts geometry to meters and density to kg/m³, then converts the result to the chosen mass unit. Choose a diameter, wall-thickness, inverse-length, or internal-fill task; quantity means identical tubes.
- V = material volume of one tube, in m³
- OD = outer diameter, converted to m
- ID = inner diameter, converted to m
- L = length per tube, converted to m
- rho = material density, converted to kg/m³
- mlb = combined tube mass in pounds
- mkg = combined tube mass in kilograms
The outer diameter and inner diameter define the wall area of the tube. The calculator subtracts the hollow inner circle from the full outer circle, then multiplies by length to get volume. Density converts volume to mass. The length task solves total target mass divided by mass per meter per tube and quantity. The fill task adds inner volume × fill density × fill fraction for every tube. Mass in kg or lb is distinct from gravitational force.
Common Tube Material Densities
Use a measured density for the material grade and temperature. The existing preset densities, including carbon steel at 7.85 g/cm³, are illustrative assumptions. Table ranges are illustrative and are not material specifications; choose Custom material density to enter any table value.
| Material | Typical Density | Use in Calculator |
|---|---|---|
| Carbon steel | 7.85 g/cm³ | 7.85 with g/cm³ selected |
| Stainless steel | 7.90 to 8.00 g/cm³ | 7.9 or 8.0 with g/cm³ selected |
| Aluminum | 2.70 g/cm³ | 2.70 with g/cm³ selected |
| Copper | 8.96 g/cm³ | 8.96 with g/cm³ selected |
| Brass | 8.4 to 8.7 g/cm³ | 8.5 with g/cm³ selected for an estimate |
| PVC | 1.35 to 1.45 g/cm³ | 1.4 with g/cm³ selected for an estimate |
Unit Conversions Used for Tube Weight
| Input Type | Conversion |
|---|---|
| Inches to centimeters | 1 in = 2.54 cm |
| Meters to centimeters | 1 m = 100 cm |
| Grams per cm³ to pounds per cm³ | 1 g/cm³ = 0.00220462 lb/cm³ |
| Kilograms per m³ to pounds per cm³ | 1 kg/m³ = 0.00000220462 lb/cm³ |
| Pounds to kilograms | 1 lb = 0.45359237 kg |
Example Calculations
Example 1: Steel tube in centimeters
Find the weight of a steel tube with an outer diameter of 10 cm, an inner diameter of 8 cm, a length of 100 cm, and a density of 7.85 g/cm³.
- Outer radius = 10 / 2 = 5 cm
- Inner radius = 8 / 2 = 4 cm
- Volume = pi * (5² – 4²) * 100
- Volume = pi * 9 * 100 = 2827.4334 cm³
- Density = 7.85 g/cm³ = 0.0173063 lb/cm³
- Mass ≈ 22.1954 kg ≈ 48.9324 lb (using unrounded values)
Example 2: Aluminum tube in inches
Find the weight of an aluminum tube with an outer diameter of 2 in, an inner diameter of 1.5 in, a length of 36 in, and a density of 2.70 g/cm³.
- Outer diameter = 2 * 2.54 = 5.08 cm
- Inner diameter = 1.5 * 2.54 = 3.81 cm
- Length = 36 * 2.54 = 91.44 cm
- Volume = pi * (2.54² – 1.905²) * 91.44 ≈ 810.8333 cm³
- Density = 2.70 g/cm³ = 0.0059525 lb/cm³
- Mass ≈ 2.1892 kg ≈ 4.8265 lb (using unrounded values)
FAQ
Is tube weight calculated from outer diameter or wall thickness?
Choose the outer/inner-diameter task or the outer-diameter/wall-thickness task. The inverse-length task also uses wall thickness. The calculator applies:
where t is the wall thickness.
Why must the inner diameter be smaller than the outer diameter?
Inner diameter must be less than outer diameter; zero is allowed for a solid round bar. Wall thickness must be positive and no greater than half the outer diameter. The half-diameter boundary also represents a solid round bar.
Does the result include coatings, threads, welds, or end fittings?
No. The result is based only on a straight hollow tube with a constant outer diameter, inner diameter, length, and density. Coatings, threads, weld seams, caps, flanges, and fittings can add extra weight and should be added separately if they matter for your estimate.
