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.
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.
What is pascal?
The pascal is the SI base unit of pressure, equal to one newton per square metre. It is used in meteorology, fluid dynamics, materials science, and all scientific pressure measurements.
Real-world uses
The pascal is the SI unit of pressure used in engineering stress analysis, materials science, and acoustics (sound pressure levels). Concrete and steel specifications list compressive strength in megapascals (MPa). Atmospheric pressure is about 101,325 Pa.
History
Named after Blaise Pascal, the French mathematician and physicist who conducted pioneering experiments on fluid pressure and vacuum in the 1640s. The pascal was adopted as the SI unit of pressure in 1971 at the 14th General Conference on Weights and Measures.
Common mistakes
Using pascals directly for everyday pressure is impractical since one pascal is a very small pressure (about the weight of a dollar bill spread over a desk). Most practical applications use kPa, hPa, or MPa instead.
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.
Worked examples
1 millibar = 100 pascal
1 pascal = 1 pascal
How to convert millibar to pascal
To convert millibar to pascal, multiply the value by 100.
To convert pascal back to millibar, multiply by 0.01.
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.
Quick reference: millibar to pascal
| millibar | pascal |
|---|---|
| 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
| millibar | pascal | |
|---|---|---|
| Car tyre | 2,200 millibar | 220,000 pascal |
| Standard atmosphere | 1,013.25 millibar | 101,325 pascal |
| Blood pressure (systolic) | 160 millibar | 16,000 pascal |
| Deep-sea submersible | 1,100,000 millibar | 110,000,000 pascal |
| Bicycle tyre | 6,200 millibar | 620,000 pascal |