Find the complete GI pipe size and weight chart below per IS 1239 Part 1, covering all standard nominal bore sizes from 15 mm (1/2 inch) to 150 mm (6 inch). Sizes are listed in both inches and millimetres, with outside diameter, wall thickness, and weight per metre for Class A (Light), Class B (Medium), and Class C (Heavy).
GI Pipe Size
Galvanised Iron (GI) pipe sizes are determined by a combination of their nominal bore (outer diameter), wall thickness, and the specific manufacturing standard to which they adhere. Generally, these pipes are categorised by their outer diameter (OD), which typically ranges from 1/2 inch to 14 inches for standard industrial applications. The two tables below give the complete sizing reference: first in inches (NPS) and then in millimetres with wall thickness for each class.
GI Pipe Sizes in Inches
Sizes in inches with their equivalent NB (mm) and outside diameter (OD) are given below. The OD is the actual outer measurement of the pipe and stays the same for all three classes (A, B, C) of a given size.
| Size (Inch / NPS) | NB (mm) | OD (Inch) | OD (mm) | Common Calling Name |
|---|---|---|---|---|
| 1/2" | 15 | 0.840 | 21.3 | Half-inch GI pipe |
| 3/4" | 20 | 1.050 | 26.7 | Three-quarter-inch GI pipe |
| 1" | 25 | 1.315 | 33.4 | 1-inch GI pipe |
| 1-1/4" | 32 | 1.660 | 42.2 | 1.25-inch GI pipe |
| 1-1/2" | 40 | 1.900 | 48.3 | 1.5-inch GI pipe |
| 2" | 50 | 2.375 | 60.3 | 2-inch GI pipe |
| 2-1/2" | 65 | 2.875 | 73.0 | 2.5-inch GI pipe |
| 3" | 80 | 3.500 | 88.9 | 3-inch GI pipe |
| 4" | 100 | 4.500 | 114.3 | 4-inch GI pipe |
| 5" | 125 | 5.563 | 141.3 | 5-inch GI pipe |
| 6" | 150 | 6.625 | 168.3 | 6-inch GI pipe |
GI Pipe Sizes in MM
Sizes in millimetres with outside diameter and wall thickness for each class per IS 1239 Part 1 are listed below. Class A is Light wall, Class B is Medium wall, and Class C is Heavy wall. The OD is identical across all three classes for a given NB. Only the wall thickness changes.
| NB (mm) | OD (mm) | Wall Class A (mm) | Wall Class B (mm) | Wall Class C (mm) |
|---|---|---|---|---|
| 15 | 21.3 | 2.00 | 2.65 | 3.25 |
| 20 | 26.7 | 2.35 | 2.65 | 3.25 |
| 25 | 33.4 | 2.65 | 3.25 | 4.05 |
| 32 | 42.2 | 2.65 | 3.25 | 4.05 |
| 40 | 48.3 | 2.90 | 3.25 | 4.05 |
| 50 | 60.3 | 2.90 | 3.65 | 4.50 |
| 65 | 73.0 | 3.25 | 3.65 | 4.50 |
| 80 | 88.9 | 3.25 | 4.05 | 4.85 |
| 100 | 114.3 | 3.65 | 4.50 | 5.40 |
| 125 | 141.3 | 4.50 | 4.85 | 5.40 |
| 150 | 168.3 | 4.50 | 4.85 | 5.40 |
GI Pipe Weight Chart
The table below lists the weight per metre (kg/m) of GI pipe for Class A (Light), Class B (Medium), and Class C (Heavy) per IS 1239 Part 1. Weights include zinc coating per IS 4736.
| NB (mm) | Size (Inch) | OD (mm) | Class A Weight (kg/m) | Class B Weight (kg/m) | Class C Weight (kg/m) |
|---|---|---|---|---|---|
| 15 | 1/2" | 21.3 | 1.22 | 1.45 | 1.68 |
| 20 | 3/4" | 26.7 | 1.58 | 1.78 | 2.12 |
| 25 | 1" | 33.4 | 2.27 | 2.71 | 3.30 |
| 32 | 1-1/4" | 42.2 | 2.93 | 3.50 | 4.27 |
| 40 | 1-1/2" | 48.3 | 3.55 | 3.90 | 4.71 |
| 50 | 2" | 60.3 | 4.45 | 5.43 | 6.65 |
| 65 | 2-1/2" | 73.0 | 6.18 | 6.83 | 8.30 |
| 80 | 3" | 88.9 | 7.69 | 9.45 | 11.27 |
| 100 | 4" | 114.3 | 10.96 | 13.42 | 16.04 |
| 125 | 5" | 141.3 | 16.46 | 17.66 | 19.59 |
| 150 | 6" | 168.3 | 19.79 | 21.27 | 23.61 |
How to use this chart: Multiply the per-metre weight by the length of the pipe to get the total weight. For a standard 6 metre piece of 50 mm Class B GI pipe: 5.43 kg/m x 6 m = 32.58 kg per piece.
Weight calculation formula: Weight (kg/m) = 0.0246615 x Wall Thickness (mm) x (OD - Wall Thickness) (mm). The constant 0.0246615 reflects the Steel density of 7,850 kg/m3. Add 1 to 3% for zinc coating to get the GI weight from the MS base weight.