QUICK CONVERSION
Inches of water column to Millimetres of water column
Enter a value to convert inches of water column to millimetres of water column, or use the right-hand input to convert in reverse.
How to convert inches of water column to millimetres of water column
Multiply the number of inches of water column by 25.4 to get millimetres of water column.
Formula: Millimetres of water column = Inches of water column × 25.4.
Common conversion values
| Inches of water column (inH₂O (4 °C)) | Millimetres of water column (mmH₂O (4 °C)) |
|---|---|
| 0 | 0 |
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 25 | 635 |
| 50 | 1,270 |
| 100 | 2,540 |
| 500 | 12,700 |
| 1000 | 25,400 |
Important measurement notes
Pressure values are absolute unit magnitudes; gauge versus absolute pressure depends on the source measurement, not the unit symbol.
Related conversions
Figures are rounded for display. For regulated or safety-critical work, confirm the relevant measurement standard and precision.