The steel pipe weight formula
This is the standard shortcut for carbon steel, with outer diameter OD and wall thickness t both in inches. The constant 10.68 folds in the density of steel and the ring geometry, so you never touch density directly. The metric twin is kg/m = 0.02466 × (OD − t) × t with dimensions in mm.
Schedule 40 and 80 weights for common sizes
| NPS | OD (mm) | SCH 40 wall | SCH 40 kg/m | SCH 80 kg/m |
|---|---|---|---|---|
| 1/2" | 21.34 | 2.77 mm | 0.73 | 0.94 |
| 3/4" | 26.67 | 2.87 mm | 1.05 | 1.38 |
| 1" | 33.40 | 3.38 mm | 1.45 | 1.88 |
| 2" | 60.33 | 3.91 mm | 3.08 | 4.01 |
| 4" | 114.30 | 4.78 mm | 7.39 | 9.57 |
| 6" | 168.28 | 5.49 mm | 14.27 | 20.27 |
Multiply kg/m by 0.672 for lb/ft. Higher schedule number means a thicker wall: SCH 80 runs 30 to 50% heavier than SCH 40 at the same outer diameter, because the extra steel goes inward, shrinking the bore, not the OD.
Two things that trip people up
- Nominal size is a label, not the OD. NPS 1" pipe actually has a 33.4 mm outer diameter. Use the real OD in the formula, never the nominal number.
- Other metals scale by density. The 10.68 constant is steel only (7.85 g/cm³). Stainless is about 1% heavier, aluminium is 2.9 times lighter, and PVC is roughly 5.6 times lighter than steel for the same dimensions.
- Have ID instead of wall? Wall thickness t = (OD − ID) / 2, then use the formula as normal.
Common questions
What is the formula for steel pipe weight per foot?
Weight per foot equals 10.68 times (outer diameter minus wall thickness) times wall thickness, with both diameter and thickness in inches. The 10.68 already bakes in the density of steel, so you only plug in the two dimensions.
What is the metric version of the pipe weight formula?
In millimetres, weight per metre equals 0.02466 times (outer diameter minus wall thickness) times wall thickness. For example a 60 mm outer diameter pipe with a 4 mm wall is 0.02466 times 56 times 4, about 5.5 kg per metre.
Why does my calculated weight differ from the manufacturer chart?
Mill tolerances under ASME are about plus or minus 10%, and catalogues often quote theoretical rather than actual weight. A gap of a few percent is normal. Also check that you used the outer diameter, not the nominal pipe size, which is only a label.
