What this calculator does
A pipe is a hollow cylinder, so the weight comes from the wall cross-section rather than the full circle. A 114.3 mm outside diameter steel pipe with a 5 mm wall weighs 13.478 kg per metre, or 80.87 kg over a 6 metre length.
Wall thickness matters more than it looks. Going from 3 mm to 8 mm on the same outside diameter takes the weight from 8.234 to 20.972 kg per metre, two and a half times, because the wall area grows as the bore shrinks from both directions at once.
The formula
The inside diameter is the outside diameter less twice the wall thickness. The wall cross-section is the area of the outer circle less the area of the bore, and multiplying that by the length and the material density gives the weight. The calculator flags the case where the wall exceeds the radius, which would leave no bore at all.
| Term | Meaning |
|---|---|
| Outside diameter (OD) | The overall diameter, which is how pipe is usually specified. |
| Wall thickness | Often given as a schedule number rather than a dimension in imperial practice. |
| Bore | The internal diameter, equal to OD minus twice the wall. |
| Kilograms per metre | The figure suppliers quote, since pipe is sold by length. |
The inputs explained
| Field | What to enter |
|---|---|
| Outside diameter (mm) | Outside diameter in millimetres. A nominal DN100 steel pipe is 114.3 mm. |
| Wall thickness (mm) | Wall thickness in millimetres. It must be less than half the outside diameter. |
| Length (m) | Total length in metres. |
| Material | Material, which sets the density. |
When to use it
Planning a lift
A 6 metre length of steel pipe can weigh more than one person should handle, and the figure decides whether machinery is needed.
Costing a fabrication
Steel is priced by weight, so the weight is effectively the material cost.
Checking a structure
Pipe used structurally contributes its own dead load, which the design must carry.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does wall thickness add?
The same pipe size at a range of wall thicknesses.
| Wall thickness | Weight per metre | Total weight | Inside diameter (bore) |
|---|---|---|---|
| 3 mm | 8.234 kg/m | 49.41 kg | 108.30 mm |
| 5 mm | 13.478 kg/m | 80.87 kg | 104.30 mm |
| 8 mm | 20.972 kg/m | 125.83 kg | 98.30 mm |
Questions
Why does the weight depend on the bore?
Because the metal is only the wall. A pipe of a given outside diameter with a large bore has a thin wall and little metal; the same outside diameter with a small bore is nearly solid. The weight comes from the difference between the two circles.
What is a pipe schedule?
An imperial convention specifying wall thickness for a given nominal size, so Schedule 40 and Schedule 80 have the same outside diameter and different walls. Look up the wall thickness for your schedule and size, then enter it here in millimetres.
Does this work for tube as well as pipe?
Yes, the geometry is identical. The difference is in how they are specified: pipe is sized by nominal bore and schedule, tube by actual outside diameter and wall. Since this calculator takes the actual dimensions, it handles both.
Why is nominal size not the actual diameter?
Historical convention. A nominal DN100 or 4 inch steel pipe actually measures 114.3 mm outside. The nominal figure once approximated the bore of a particular wall thickness and has been kept as a naming system long after the dimensions drifted.
For solid bar and plate, see the metal weight calculator. For the water a pipe holds, see the pipe volume calculator.