hectopascal (hPa)
1 hectopascal = 100 pascals
What is hectopascal?
A hectopascal is a pressure unit equal to 100 pascals, numerically identical to the millibar. It is the standard unit for atmospheric pressure reports in modern meteorology and aviation weather data.
Notes: Same as mbar
Real-world uses
Hectopascals are the modern meteorological standard for atmospheric pressure reporting, used by the World Meteorological Organization and most national weather services. Standard atmospheric pressure is 1013.25 hPa. Altimeter settings in aviation outside the US use hPa (QNH).
History
The hectopascal was promoted by the WMO beginning in 1982 as a replacement for the millibar, aligning meteorology with the SI system. Since 1 hPa equals exactly 1 mbar, the transition required no changes to numerical readings or instruments.
Common mistakes
Not realizing that 1 hPa = 1 mbar exactly. The switch from millibars to hectopascals changed only the name, not the numerical values. Also, some people confuse hPa with kPa; 1 kPa = 10 hPa.
When is this conversion used?
Converting hectopascal to pascal is useful in the pressure domain when comparing values across different measurement standards or applying formulas that require a specific unit.
How to convert hectopascal to pascal
To convert hectopascal to pascal, multiply the value by 100.
Conversion formula (from base unit)
x * 100.0
Measurement standards
The pascal (Pa) is the SI derived unit of pressure, defined as one newton per square metre. The World Meteorological Organization mandates the hectopascal (hPa) for atmospheric pressure reporting in aviation and weather services.
Did you know?
The pressure at the bottom of the Mariana Trench, nearly 11 km deep, exceeds 1,086 bar — over a thousand times atmospheric pressure. At this depth, water is compressed by about 5%, making it measurably denser than at the surface.
| hectopascals | pascals |
|---|---|
| 0.1 | 10 |
| 0.5 | 50 |
| 1 | 100 |
| 2 | 200 |
| 5 | 500 |
| 10 | 1,000 |
| 25 | 2,500 |
| 50 | 5,000 |
| 100 | 10,000 |
| 250 | 25,000 |
| 500 | 50,000 |
| 1,000 | 100,000 |
Common values
| hectopascals | pascals | |
|---|---|---|
| Car tyre | 2,200 hectopascals | 220,000 pascals |
| Standard atmosphere | 1,013.25 hectopascals | 101,325 pascals |
| Blood pressure (systolic) | 160 hectopascals | 16,000 pascals |
| Deep-sea submersible | 1,100,000 hectopascals | 110,000,000 pascals |
| Bicycle tyre | 6,200 hectopascals | 620,000 pascals |
Full hectopascal conversion table
| Unit | Value | Factor |
|---|---|---|
| pascal | 1 hPa = 100 Pa | × 100 |
| kilopascal | 1 hPa = 0.1 kPa | × 0.1 |
| bar | 1 hPa = 0.001 bar | × 0.001 |
| pound per square inch | 1 hPa = 0.01450377 psi | × 0.01450377 |
| atmosphere | 1 hPa = 0.00098692 atm | × 0.00098692 |
| millibar | 1 hPa = 1 mbar | × 1 |
| torr | 1 hPa = 0.75006168 Torr | × 0.75006168 |
| inch of mercury | 1 hPa = 0.02952998 inHg | × 0.02952998 |
| megapascal | 1 hPa = 0.0001 MPa | × 0.0001 |