Millimeters Of Water to Bars (mmH₂O to bar)
1 millimeter of water equals 0.0000980665 bars exactly.
How to convert millimeters of water to bars
To convert millimeters of water to bars, multiply the number of millimeters of water by 0.0000980665. This factor is exact. To go the other way, multiply bars by 10,197.16213 (rounded).
bars = millimeters of water × 0.0000980665
Example: 10 millimeters of water = 0.000980665 bars.
About these units
Millimeter Of Water (mmH₂O)
Exactly 9.80665 pascals by convention. Used for very low pressures.
A column of water one millimetre tall presses down with 9.80665 Pa under the usual convention, which assumes a density of 1,000 kg/m3 for water at its densest, near 4 degrees Celsius, and standard gravity. NIST marks this conventional millimeter of water as an exact factor. Using the true density of water at 4 degrees Celsius, 999.972 kg/m3, gives about 9.80638 Pa instead, so the two differ in the fifth digit.
Because the unit is so small it suits very low pressures, such as the draft in a duct or a chimney, filter drops and sensitive gauges. It also gives waterproof ratings for fabric, where a tent or jacket rated to some number of millimetres can resist that height of water before leaking. Pressure in this form is often written mmH2O, mmWG or mmWC. Ten millimetres of water is about 98 Pa, or roughly 0.1 percent of one standard atmosphere.
1 millimeter of water = 9.80665 pascals (exactly).
Sources: Wikipedia: Millimetre of water; NIST SP 811, Appendix B.8
Bar (bar)
Exactly 100,000 pascals, close to atmospheric pressure at sea level. Used for tire pressure, diving and industrial gauges.
Bar began as a name that meant different things to different people. It comes from the Ancient Greek baros, weight, and from 1793 to 1795 an early metric system used bar for a unit of mass equal to the modern tonne. The pressure bar was introduced by the Norwegian meteorologist Vilhelm Bjerknes, a founder of modern weather forecasting, who defined it as one megadyne per square centimeter. Some earlier writers had used bar for one dyne per square centimeter, a source of confusion.
The bar is a metric unit but not part of the SI, and its official symbol is simply bar, since the old b clashes with the barn and the bit. It has been legally recognized in EU countries since 2004, although NIST deprecates it except for limited use in meteorology.
Its size is handy because 1 bar is slightly less than average sea-level pressure, which is about 1.013 bar. In scuba diving every 10 meters of seawater adds about 1 bar and a full standard tank holds about 200 bar. Tire pressure and turbocharger boost are often quoted in bar outside the US.
1 bar = 100,000 pascals (exactly).
Sources: Wikipedia: Bar (unit); Wikipedia: Atmospheric pressure
Related conversions
- Bars to millimeters of water (reverse)
- Millimeters of water to pascals
- Millimeters of water to kilopascals
- Millimeters of water to standard atmospheres
- Millimeters of water to PSI
- Pascals to bars
- Kilopascals to bars
- Standard atmospheres to bars
- PSI to bars
- Hectopascals to bars
- Megapascals to bars
- Millibars to bars
- Torr to bars
- Millimeters of mercury to bars
- Inches of mercury to bars
- Gigapascals to bars
- Kilopounds per square inch to bars
See all pressure units.