This calculator allows you to convert from Pound-force/square inch to Millimeter water (4°C) and in a reverse direction. To convert from Pound-force/square inch to Millimeter water (4°C), enter the amount of Pound-force/square inch into the first input and to convert from Millimeter water (4°C) to Pound-force/square inch, enter the amount of Millimeter water (4°C) into the second input.