millibar (mbar)
1 millibar = 100 pascals
What is millibar?
A millibar is a pressure unit equal to one thousandth of a bar. It is the standard unit for atmospheric pressure in meteorology and weather forecasting, particularly in aviation and marine contexts.
Notes: Meteorology unit
Real-world uses
Millibars are the traditional unit in meteorology for reporting atmospheric pressure, particularly in weather maps and hurricane tracking. Standard atmospheric pressure is 1013.25 mbar, and tropical cyclones can have central pressures below 900 mbar.
History
The millibar was introduced by Sir Napier Shaw in 1909 for meteorological use. It dominated weather reporting throughout the 20th century. Since 1982, the WMO has officially recommended hectopascals instead, though both represent exactly 100 Pa.
Common mistakes
Not realizing that 1 millibar = 1 hectopascal exactly. Meteorological services have largely switched to hPa, but the numerical values are identical. Also, assuming lower millibar values mean calmer weather—lower pressure often indicates storms.
When is this conversion used?
Converting millibar 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 millibar to pascal
To convert millibar 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.
| millibars | 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
| millibars | pascals | |
|---|---|---|
| Car tyre | 2,200 millibars | 220,000 pascals |
| Standard atmosphere | 1,013.25 millibars | 101,325 pascals |
| Blood pressure (systolic) | 160 millibars | 16,000 pascals |
| Deep-sea submersible | 1,100,000 millibars | 110,000,000 pascals |
| Bicycle tyre | 6,200 millibars | 620,000 pascals |
Full millibar conversion table
| Unit | Value | Factor |
|---|---|---|
| pascal | 1 mbar = 100 Pa | × 100 |
| kilopascal | 1 mbar = 0.1 kPa | × 0.1 |
| bar | 1 mbar = 0.001 bar | × 0.001 |
| pound per square inch | 1 mbar = 0.01450377 psi | × 0.01450377 |
| atmosphere | 1 mbar = 0.00098692 atm | × 0.00098692 |
| hectopascal | 1 mbar = 1 hPa | × 1 |
| torr | 1 mbar = 0.75006168 Torr | × 0.75006168 |
| inch of mercury | 1 mbar = 0.02952998 inHg | × 0.02952998 |
| megapascal | 1 mbar = 0.0001 MPa | × 0.0001 |