About

Hydraulic engineers and pump specialists rely on accurate conversions between system pressure (MPa) and pump head (mH2O). While pressure gauges often read in Pascals, pump curves and tank specifications frequently reference meters of water column. This distinction is critical when sizing submersible pumps or designing municipal water towers, where the physical height of the fluid directly correlates to the required pressure capability.

This tool assumes standard water density at its maximum density point (4°C). At this temperature, water density is effectively 1000 kg/m³, providing the baseline for the conversion factor used here. Engineers working with hot water or brine should note that fluid density variations will slightly alter the true physical head, though this tool provides the standard hydraulic reference.

Formulas

The calculation uses the hydrostatic pressure formula rearranged for height (head). Given standard gravity g and water density ρ, the relationship is:

1 MPa ≈ 101.971621 mH2O

The explicit formula used for this tool is:

H = P_MPa × 101.971621

Reference Data

Pressure (MPa)	Head (mH2O)	Typical Scenario
0.1	10.20	2-story building supply
0.2	20.39	Residential mains pressure
0.3	30.59	Standard irrigation sprinkler
0.4	40.79	Small fire suppression system
0.5	50.99	Mid-rise booster pump
0.6	61.18	City water grid mainline
0.8	81.58	Industrial process water
1.0	101.97	High-head deep well pump
1.5	152.96	Mining dewatering
2.0	203.94	Reverse osmosis feed
2.5	254.93	Hydraulic mining
5.0	509.86	Hydroelectric penstock

Frequently Asked Questions

This tool uses the standard reference at 4°C, where water density is highest (approx 1000 kg/m³). Warmer water is less dense, meaning 1 MPa would result in a slightly higher head (more meters) to exert the same pressure.

mH2O helps engineers visualize physical height. If a pump needs to push water up 50 meters, it is easier to select a pump rated for 50 mH2O than one rated for 0.49 MPa, although they are equivalent.

No. Saltwater is denser (approx 1025 kg/m³). For seawater, you would need to divide the result by the specific gravity of the saltwater (approx 1.025) to get the correct head.

The conversion factor 101.971621 is used for high precision, but in practical plumbing, friction losses (head loss) are often more significant than decimal precision.