Bar to Metres Head Converter
Convert pressure in bar to head in metres of water column (mH2O, also written m wc, or mca on Spanish and Portuguese datasheets). For water, multiply bar by 10.2. For other liquids, divide by the specific gravity as well.
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How It Works
Metric pump curves give head in metres, while gauges and system specifications read in bar. One bar supports a column of water just over 10 metres high. That is also why no pump can lift water by suction more than about 10.33 m at sea level: standard atmospheric pressure, 1.01325 bar, only supports that much, and in practice the limit is lower still.
The conversion divides the pressure by the liquid's specific weight: h = P / (ρ × g). A liquid with a higher specific gravity (SG) stands lower for the same pressure, so divide the water figure by the SG.
Formula
Metres of head = bar × 10.1972 ÷ SG
The 10.1972 factor uses the conventional water column (1,000 kg/m³, 9.80665 m/s²), the basis of the mH2O unit. Water at 20 °C (SG 0.9982) gives 10.2156 m per bar.
Worked Example
A booster set raises the pressure by 4.5 bar. The head it adds, in water, is:
4.5 × 10.1972 = 45.8874 m of head
Bar to Metres Head Table (water, SG 1.0)
| bar | m | ft |
|---|---|---|
| 0.1 bar | 1.01972 m | 3.34553 ft |
| 0.25 bar | 2.54929 m | 8.36381 ft |
| 0.5 bar | 5.09858 m | 16.7276 ft |
| 1 bar | 10.1972 m | 33.4553 ft |
| 1.5 bar | 15.2957 m | 50.1829 ft |
| 2 bar | 20.3943 m | 66.9105 ft |
| 2.5 bar | 25.4929 m | 83.6381 ft |
| 3 bar | 30.5915 m | 100.366 ft |
| 4 bar | 40.7886 m | 133.821 ft |
| 5 bar | 50.9858 m | 167.276 ft |
| 6 bar | 61.183 m | 200.732 ft |
| 8 bar | 81.5773 m | 267.642 ft |
| 10 bar | 101.972 m | 334.553 ft |
Metres of Head per Bar by Liquid
The same 1 bar gives a different height of column for each liquid. For a liquid not listed, take its SG from the supplier datasheet and enter it above.
| Liquid | 1 bar |
|---|---|
| Water, conventional (SG 1.000) | 10.1972 m |
| Water at 60 °F / 15.6 °C (SG 0.9990) | 10.2074 m |
| Water at 20 °C / 68 °F (SG 0.9982) | 10.2156 m |
| Water at 60 °C / 140 °F (SG 0.9832) | 10.3714 m |
| Water at 80 °C / 176 °F (SG 0.9718) | 10.4931 m |
| Seawater (SG 1.025) | 9.94845 m |
SG here is relative to 1,000 kg/m³. A datasheet SG referenced to water at 60 °F differs by 0.1%, which you can ignore.
Going the other way? Use the metres head to bar converter. For the head a pump has to deliver, including pipe friction, use the total dynamic head calculator.
FAQ
Common questions about converting bar to metres of head.
Frequently Asked Questions
How do I convert bar to metres of head?
Multiply bar by 10.1972 for water. For example, 3 bar × 10.1972 = 30.5916 m. For another liquid, divide the result by its specific gravity.
How many metres of head is 1 bar?
1 bar equals 10.1972 metres of water column on the conventional basis, or 10.2156 m with water at 20 °C. 10.2 is the usual rounded figure and 10 is the rule of thumb.
Is mH2O the same as metres of head?
For water, yes. mH2O, m wc and mca (metros de columna de agua) all mean head in metres of water. Metres of head is the general term for any liquid, which is why the specific gravity matters when the liquid is not water.
How high can a pump lift water by suction?
No more than 10.3323 m at sea level in theory, because that is the head standard atmospheric pressure (1.01325 bar) can support. In practice the limit is lower, because of the water's vapour pressure, friction in the suction pipe and the pump's NPSH requirement.
Does pipe size change the conversion?
No. Pressure and head convert through the liquid's density and gravity alone. Pipe size changes how much head is lost to friction along the pipe, which is a separate calculation.
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