Convert Gigapascal to Millimeter of Water (GPa to mmH2O)

Pressure is the force applied perpendicular to a surface per unit area: P = F / A. The SI unit is the pascal (Pa), equal to one newton per square metre (1 Pa = 1 N/m²). Practical applications use larger units: the bar (1 bar = 100,000 Pa, close to standard atmospheric pressure), atmosphere (atm) (1 atm = 101,325 Pa), and psi (pounds per square inch, used in the US for tire and gas pressures). Blood pressure is measured in mmHg (millimetres of mercury), also called torr.

The gigapascal (symbol: GPa) is an SI-derived unit of pressure equal to one billion (10⁹) pascals. It is widely used in material science, structural engineering, mechanical engineering, and geology to express very high pressures and the elastic modulus of materials. The gigapascal uses the SI prefix giga, representing a factor of one billion.

One gigapascal is equal to 1,000,000,000 pascals, 1,000 megapascals, 1,000,000 kilopascals, 10,000 bars, and 145,037.738 pounds per square inch. The gigapascal is the standard unit for reporting the strength and stiffness of engineering materials.

The millimeter of water (symbol: mmH₂O or mmH2O) is a non-SI unit of pressure defined as the pressure exerted by a one-millimeter column of water under standard gravity. It is commonly used in ventilation systems, clean rooms, HVAC engineering, and laboratory instruments to measure small pressure differences. Although the pascal is the SI unit of pressure, the millimeter of water remains a practical unit for low-pressure applications. It is based on the concept of a water column.

One millimeter of water is equal to 9.80665 pascals, 0.1 centimeter of water, 0.0000980665 bar, 0.00142233 pounds per square inch, and 0.00980665 kilopascal. The millimeter of water is widely used for measuring very low gas and liquid pressures.