1 inch (DN 25) pipe dimensions & weight
1 inch (DN 25) steel pipe has an outside diameter of 33.4 mm (1.315 in) in every schedule. Below: wall thickness, inside diameter, weight per metre and water capacity for each ASME B36.10M / B36.19M schedule.
| Schedule | Wall (mm) | Wall (in) | ID (mm) | CS kg/m | CS lb/ft | SS 304 kg/m | Water L/m |
|---|---|---|---|---|---|---|---|
| Sch 5S | 1.65 | 0.065 | 30.10 | 1.29 | 0.87 | 1.30 | 0.71 |
| Sch 10S | 2.77 | 0.109 | 27.86 | 2.09 | 1.40 | 2.11 | 0.61 |
| STD | 3.38 | 0.133 | 26.64 | 2.50 | 1.68 | 2.53 | 0.56 |
| Sch 40 | 3.38 | 0.133 | 26.64 | 2.50 | 1.68 | 2.53 | 0.56 |
| XS | 4.55 | 0.179 | 24.30 | 3.24 | 2.18 | 3.27 | 0.46 |
| Sch 80 | 4.55 | 0.179 | 24.30 | 3.24 | 2.18 | 3.27 | 0.46 |
| Sch 160 | 6.35 | 0.250 | 20.70 | 4.24 | 2.85 | 4.28 | 0.34 |
| XXS | 9.09 | 0.358 | 15.22 | 5.45 | 3.66 | 5.51 | 0.18 |
CS = carbon steel (7.85 g/cm³). SS 304 at 7.93 g/cm³; for 316 multiply CS weight by 1.017. Water capacity = internal volume per metre.
Matching 1" flanges and fittings
| Class 150 flange | OD 110 mm · thk 12.7 mm · PCD 79.4 mm · 4 × 1/2" bolts |
| Class 300 flange | OD 125 mm · thk 15.9 mm · PCD 88.9 mm · 4 × 5/8" bolts |
| B16.9 fittings | 90° LR 38 mm · 45° LR 22 mm · 90° SR 25 mm · tee 38 mm · reducer 51 mm · cap 38 mm |
Full tables: Class 150 · Class 300 · B16.9 fittings.
Frequently asked questions
What is the OD of 1 inch pipe?
1 inch (DN 25) pipe has an outside diameter of 33.4 mm (1.315 in), regardless of schedule.
What is the wall thickness of 1 inch Schedule 40 pipe?
3.38 mm (0.133 in), giving an inside diameter of 26.64 mm.
How much does 1 inch Schedule 40 pipe weigh?
About 2.50 kg/m (1.68 lb/ft) in carbon steel, or 15.0 kg for a 6 m length.
What is the wall thickness of 1 inch Schedule 80 pipe?
4.55 mm, with an inside diameter of 24.30 mm and weight of 3.24 kg/m.
Last updated 2026-11-02