A millibar is 100 pascals.
Millibars to Bars Converter — mbar to bar
Convert Millibar (mbar) to Bar (bar) using the exact conversion factor (1 millibar = 0.001 bar). See the formula, worked examples, conversion table, history, and common uses.
Millibars to Bars converter
Converter
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mercury columns, water columns, and engineering pressure units.
Context values
Some unit families need one extra value for a physically accurate result.
A bar is exactly 100,000 pascals.
Result = input x 100 / 100000.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Millibars to Bars
Millibar and Bar both show up on pressure gauges — psi is standard on US tire and tool specifications, while bar is the everyday pressure unit across most of the rest of the world. Specifically: A millibar is 100 pascals, and a bar is exactly 100,000 pascals.
Formula
bars = millibars × 0.001
This factor comes from each unit's defined relationship to the category's base unit: 1 millibar equals 100 base units, and 1 bar equals 100000 base units, so dividing one by the other gives the direct millibar-to-bar factor of 0.001.
Simple example
1 mbar × 0.001 = 0.001 bar
1 millibar = 0.001 bars.
Real-world example
35 mbar × 0.001 = 0.035 bar
35 millibars = 0.035 bars.
Conversion table
| Millibar (mbar) | Bar (bar) |
|---|---|
| 1 mbar | 0.001 bar |
| 5 mbar | 0.005 bar |
| 10 mbar | 0.01 bar |
| 25 mbar | 0.025 bar |
| 50 mbar | 0.05 bar |
| 100 mbar | 0.1 bar |
Reverse conversion: Bar to Millibar
0.001 bar × 1000 = 1 mbar
0.001 bars = 1 millibar.
millibars = bars × 1000
For a page dedicated to this direction, see Bar to Millibar.
Understanding the Millibar (mbar)
A millibar is 100 pascals.
Understanding the Bar
Bar (bar) measures pressure. A bar is defined as exactly 100,000 pascals, close to (but distinct from) one standard atmosphere (101,325 Pa). It is classified as a Non-SI metric unit accepted for use with SI.
Where it's used: Widely used in Europe and most of the world for tire pressure, weather, and industrial pressure
Uses of the Bar today
- Tire pressure specifications outside the US
- Meteorology (weather maps commonly use millibars, hPa)
- Industrial and hydraulic pressure ratings in metric-system countries
History of the Bar
The bar was proposed by Norwegian meteorologist Vilhelm Bjerknes around 1906 as a convenient round pressure unit close to atmospheric pressure, derived from the CGS unit system (one bar equals one million dynes per square centimeter).
Though not an SI unit, the bar remains in wide practical use, particularly in meteorology (as the millibar, now more often written as the equivalent hectopascal) and in tire and hydraulic pressure specifications across most of the world.
Historical origin. Bar was not the invention of a single named person; it developed through the process described above.
Bar — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the bar among accepted non-SI pressure units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many bars are in 1 millibar?
1 millibar equals 0.001 bars, using the exact defined conversion factor rather than an estimate.
How do I convert millibar to bar?
Multiply the millibar value by 0.001. The converter above does this instantly to whatever precision you set.
How do I convert bar back to millibar?
Use the reverse factor: 1 bar equals 1,000 millibars. You can also use the swap control in the converter above to flip the direction instantly.
What is a millibar?
Millibar (mbar) is a unit of pressure.
What is a bar?
Bar (bar) measures pressure. A bar is defined as exactly 100,000 pascals, close to (but distinct from) one standard atmosphere (101,325 Pa). It is classified as a Non-SI metric unit accepted for use with SI.
Is the millibar to bar conversion exact?
Yes. A bar is defined as exactly 100,000 pascals, close to (but distinct from) one standard atmosphere (101,325 Pa). That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.