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To convert a pressure from pascals (Pa) to bar, divide by 100,000.
The bar is defined as exactly 100,000 Pa, so the conversion is an exact five-place decimal shift with no rounding anywhere. Equivalently, multiply by 10⁻⁵.
Because the definition is exact, the anchors are too:
A pressure transmitter on a water main outputs 250,000 Pa, and the plant's mimic display is configured in bar:
Two and a half bar is a typical mains supply pressure — a value an operator recognizes at a glance, where a quarter of a megapascal would need a moment's thought.
| Pa | bar |
|---|---|
| 1 | 0.00001 |
| 1,000 | 0.01 |
| 100,000 | 1 |
| 101,325 | 1.01325 |
| 250,000 | 2.5 |
| 1,000,000 | 10 |
The bar is not an SI unit, and it has survived anyway for a practical reason: it is almost exactly one atmosphere, so pressures expressed in bar carry immediate physical intuition. Two bar is "twice the air around you." Six hundred thousand pascals is not. That intuition is why gauges, pressure switches, relief valves and pneumatic components across Europe are marked in bar while the calculations behind them, the standards that govern them and the sensors inside them work in pascals — making Pa→bar one of the most frequently automated conversions in industrial software.
The exactness of the factor is worth appreciating. Most pressure conversions involve empirical constants (mercury density, the pound-force, gravity) that force rounding decisions; this one involves none, so a converted value loses no precision at all and can be converted back and forth indefinitely. What still requires care is the neighboring units, which sit at deceptively similar magnitudes: a bar is 100,000 Pa, a standard atmosphere is 101,325 Pa, and a technical atmosphere (at, still found on older German equipment) is 98,066.5 Pa. Treating them as one unit introduces errors of 1–2% — invisible in a tire but consequential in a calibration certificate or a pressure-vessel calculation.
How many pascals are in one bar? One bar (bar) contains 105 pascals (Pa) — the inverse of the factor above. Multiplying by 10-5 takes you from pascals to bar; multiplying by 105 brings you back.
Put in words: one pascal equals 10-5 bar, so the pascal is the smaller unit of this pair. Converting between them never changes the amount of pressure being measured — only the size of the unit you count it in.
A pascal (Pa) is the standard unit of pressure in the International System of Units (SI). It is a derived unit, meaning other base units define it.
The primary pascal definition is one newton of force applied over an area of one square meter (1 Pa = 1 N/m2).
Because a single pascal represents a very small amount of pressure, it is most often seen in multiples.
The most common multiples are the kilopascal (kPa), equal to 1,000 pascals, and the megapascal (MPa), equal to 1,000,000 pascals.
These units are widely used in fields from weather forecasting to material science.
The pascal (Pa) unit is named in honor of Blaise Pascal, a key 17th-century French mathematician, physicist, and inventor.
His groundbreaking work on how fluids behave under pressure (known as hydrodynamics and hydrostatics) and his formulation of Pascal's Law were essential to our modern understanding of pressure.
To understand just how small a single pascal is, here are two real-world examples:
This shows why, for most everyday measurements (like tire pressure or weather), the larger kilopascal (kPa) is much more practical.
The bar is a metric unit of pressure.
It is defined as exactly 100 kilopascals (kPa), or 100,000 Pascals (Pa).
Although it is not an official part of the International System of Units (SI), it is widely accepted for use with the SI. The bar is a popular unit for measuring pressure because it is very close to the average atmospheric pressure on Earth at sea level.
The term "bar" comes from the Greek word βάρος (baros), which means "weight."
The unit was introduced by British meteorologist William Napier Shaw in 1909. It is still widely used in meteorology, oceanography, and engineering.
A common point of confusion is the difference between a bar and a standard atmosphere (atm).
While they are very close in value, they are not the same:
This means 1 bar is approximately equal to 0.987 atm. Because it's so close to atmospheric pressure and is a round number (100 kPa), the bar is a very convenient unit for many applications.
The bar is a versatile unit used to measure pressure in many industrial and everyday contexts.
Common examples include:
Here are some quick reference conversions from pascal (Pa) to bar (bar):
| pascals | bar |
|---|---|
| 0.000001 Pa | 10-11 bar |
| 0.001 Pa | 10-8 bar |
| 0.1 Pa | 10-6 bar |
| 1 Pa | 10-5 bar |
| 2 Pa | 0.00002 bar |
| 3 Pa | 0.00003 bar |
| 4 Pa | 0.00004 bar |
| 5 Pa | 0.00005 bar |
| 6 Pa | 0.00006 bar |
| 7 Pa | 0.00007 bar |
| 8 Pa | 0.00008 bar |
| 9 Pa | 0.00009 bar |
| 10 Pa | 10-4 bar |
| 20 Pa | 0.0002 bar |
| 30 Pa | 0.0003 bar |
| 40 Pa | 0.0004 bar |
| 50 Pa | 0.0005 bar |
| 100 Pa | 0.001 bar |
| 1000 Pa | 0.01 bar |
| 10000 Pa | 0.1 bar |
Engineering datasheets across Europe write pascal to bar several different ways. The calculation is the same in every one of them.
| Language | Written as | Unit names |
|---|---|---|
| French | Pa en bar | pascal → bar |
| Spanish | Pa a bar | pascal → bar |
| Dutch | Pa naar bar | pascal → bar |
| German | Pa in bar | Pascal → Bar |
| Polish | Pa na bar | paskal → bar |
For all Pressure converters, choose units using the From/To dropdowns above.