Pièzes to Bars (pz to bar)

1 pièze equals 0.01 bars exactly.

1 pièze = 0.01 bars

How to convert pièzes to bars

To convert pièzes to bars, multiply the number of pièzes by 0.01. This factor is exact. To go the other way, multiply bars by 100.

bars = pièzes × 0.01

Example: 10 pièzes = 0.1 bars.

About these units

Pièze (pz)

French (Ancien Régime)Historical unit (no longer in standard use)

Exactly 1,000 pascals (1 kPa): the pressure unit of the old French meter-tonne-second (MTS) system.

French metrologists coined the pièze, symbol pz, for pressure in the metre-tonne-second (MTS) system, which was France's legal system from 1919 to 1961. The Soviet Union adopted the same system in 1933 and abolished it in 1955. The name is French, and Wikipedia does not explain its origin further.

The MTS system used large units suited to industry rather than laboratories, and the pièze follows that pattern. It is defined as one sthène of force per square metre, which works out to exactly 1,000 pascals, or one kilopascal. That is the same as 10 millibars or one centibar, about 7.5 torr, and roughly 0.145 pounds per square inch.

Compared with everyday pressures, one pièze is about one hundredth of standard atmospheric pressure, so steam boilers and hydraulic machinery of the period would be quoted in tens or hundreds of pièzes. The unit disappeared with the MTS system, and the kilopascal now fills the same role.

1 pièze = 1,000 pascals (exactly).

Sources: Wikipedia: Pièze; Wikipedia: Metre-tonne-second system of units

Bar (bar)

Metric (SI)Current unit

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

See all pressure units.