hectopascal
Pressureexact by definition
The hectopascal is exactly 100 pascals, and exactly equal to the millibar. It is the unit of surface atmospheric pressure in every modern meteorological service: standard sea level pressure is 1013.25 hPa, and a deep low might read 950 hPa.
| 1 | 0.1 |
Where the unit came from
Meteorology switched from millibars to hectopascals in the 1980s to become formally SI, having noticed that the two are numerically identical so no chart, no forecaster and no instrument dial had to change. It is the least disruptive unit conversion in history.
One hectopascal in every pressure unit
| 1,000 | microbar (μbar) | |
| 1,000 | barye (Ba) | |
| 750.062 | millitorr (mTorr) | |
| 100 | pascal (Pa) | |
| 10.1972 | millimeter of water column (mmH₂O) | |
| 2.08854 | pound per square foot (lb/ft²) | |
| 1.01972 | centimeter of water column (cmH₂O) | |
| 1 | hectopascal (hPa)this unit | |
| 1 | millibar (mbar) | |
| 0.750062 | torr (Torr) | |
| 0.750062 | millimeter of mercury (mmHg) | |
| 0.401463 | inch of water column (in w.g.) | |
| 0.1 | kilopascal (kPa) | |
| 0.0334553 | foot of water column (ft H₂O) | |
| 0.02953 | inch of mercury (inHg) | |
| 0.0145038 | pound per square inch (psi) | |
| 0.0101972 | meter of water column (m H₂O) | |
| 0.01 | decibar (dbar) | |
| 0.00101972 | kilogram-force per square centimeter (kgf/cm²) | |
| 0.001 | bar (bar) | |
| 0.000986923 | atmosphere (atm) | |
| 0.0001 | megapascal (MPa) | |
| 0.0000145038 | kip per square inch (ksi) | |
| 1.00000e-07 | gigapascal (GPa) | |
| 1.45038e-08 | million pounds per square inch (Mpsi) |
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