Bars to Gigapascals (bar to GPa)

1 bar equals 0.0001 gigapascals exactly.

1 bar = 0.0001 gigapascals

How to convert bars to gigapascals

To convert bars to gigapascals, multiply the number of bars by 0.0001. This factor is exact. To go the other way, multiply gigapascals by 10,000.

gigapascals = bars × 0.0001

Example: 10 bars = 0.001 gigapascals.

About these 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

Gigapascal (GPa)

Metric (SI)Current unit

One billion pascals. Used for the stiffness (Young's modulus) of materials; steel is about 200 GPa.

Blaise Pascal's name was attached to the SI unit of pressure in 1971, when the 14th General Conference on Weights and Measures adopted it for one newton per square metre. A gigapascal is a billion of them, 10^9 Pa, which is a size that makes sense only for solid materials and deep-Earth conditions, not for weather or tyres.

Materials scientists quote stiffness in it. Wikipedia's table of Young's modulus lists structural steel at about 200 GPa and diamond at 1,220 GPa, while geophysicists use gigapascals for tectonic stresses and pressures inside the planet. Atmospheric pressure of about 101,325 Pa is therefore about 0.0001 GPa, and one gigapascal is roughly 145,000 psi or 145 ksi. A gigapascal also equals one thousand megapascals, the unit in which concrete and steel strengths are usually written.

1 gigapascal = 1,000,000,000 pascals (exactly).

Sources: Wikipedia: Pascal (unit); Wikipedia: Pounds per square inch

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