How do you calculate the weight of a pipe?
Pipe weight is calculated as π/4 × (outside diameter² − inside diameter²) × length × density, where inside diameter is the outside diameter minus twice the wall thickness. For carbon steel in millimetres, the shortcut is (OD − wall) × wall × 0.02466 kg per metre.
Key Takeaways
- The general formula is π/4 × (OD² − ID²) × length × density, with ID = OD − 2 × wall thickness.
- The carbon steel shortcut is (OD − wall) × wall × 0.02466 kg per metre, with OD and wall in millimetres.
- Wall thickness comes from the schedule, not the nominal size — a 6 inch SCH 40 and a 6 inch SCH 80 pipe share an outside diameter but not a weight.
- Stainless at 7.93 to 8.00 g/cm³ runs about 2 per cent heavier than carbon steel for identical geometry.
- Titanium Grade 2 at 4.51 g/cm³ weighs roughly 43 per cent less than carbon steel for the same dimensions.
- Mill tolerance means the weighed figure can differ by up to about 5 per cent on thin-wall pipe.
The formula and the shortcut
The exact method is straightforward: subtract the bore from the outer circle, then multiply by length and density. With outside diameter D and wall thickness t in millimetres, inside diameter is D − 2t, and volume per metre is π/4 × (D² − (D − 2t)²) × 1000 cubic millimetres.
The shortcut most estimators use collapses that to a single line for carbon steel: weight in kg per metre = (D − t) × t × 0.02466. The constant carries both π and the 7,850 kg/m³ density of carbon steel. For stainless multiply the result by roughly 1.02; for titanium by 0.575.
Worked example. A 6 inch SCH 40 pipe has an outside diameter of 168.3 mm and a wall of 7.11 mm. (168.3 − 7.11) × 7.11 × 0.02466 gives about 28.3 kg per metre, so a 6 metre length weighs roughly 170 kg.
Where the wall thickness comes from
The most common error is entering a nominal size and guessing the wall. Nominal pipe size fixes the outside diameter; the schedule fixes the wall. Those are independent, which is why a 6 inch SCH 40 and a 6 inch SCH 160 pipe bolt to the same flange but weigh very different amounts.
Take the wall from the pipe schedule chart, which lists outside diameter and wall thickness for every common schedule from SCH 10 to SCH XXS. On stainless, note that the S-series schedules are not identical to the carbon-steel series at every size.
Frequently Asked Questions
Weight per metre equals pi divided by four, times outside diameter squared minus inside diameter squared, times density. For carbon steel with dimensions in millimetres the shortcut is outside diameter minus wall thickness, times wall thickness, times 0.02466.
Yes. Select the material and the correct density is applied automatically, covering carbon steel, 304, 316, duplex, super duplex, Inconel, Monel, copper, cupro-nickel, titanium and aluminium.
Mill tolerance on wall thickness is normally plus or minus 12.5 per cent on seamless pipe, and mills tend to run to the plus side. On thin-wall pipe that alone can account for several per cent.
The S suffix denotes the stainless steel schedule series, which specifies thinner walls than the carbon steel series at some sizes. Supplying SCH 10 where 10S was specified is a dimensional non-conformance.