What this pressure converter does
Enter one value and its unit, and this converter instantly shows the same pressure in the seven units people actually use: pascal (Pa), kilopascal (kPa), bar, psi (pound per square inch), atmosphere (atm), millimeter of mercury (mmHg) and millibar (mbar). Every calculation runs in your browser — nothing is sent to a server.
It helps when you inflate a tire with a psi gauge but the car manual asks for bar, when a weather report quotes millibars or hectopascals, when you read blood pressure in mmHg, or when a technical manual mixes kPa and atmospheres.
How to use it
- Type the amount in the Value field (a dot or a comma both work for decimals).
- Pick the source unit from the dropdown.
- Read the equivalents: the dark card shows the result in pascals — the SI base unit — and the white cards show every other unit.
- Tap any card to copy its value and symbol to the clipboard.
The method and the factors
Every pressure conversion routes through one shared base unit: the pascal, which is one newton per square meter (N/m²). Your value is first converted to pascals by multiplying by the source unit’s factor, then divided by the target unit’s factor. These are the exact factors to the pascal:
| Unit | Symbol | Equals (Pa) |
|---|---|---|
| Pascal | Pa | 1 |
| Millibar | mbar | 100 |
| Millimeter of mercury | mmHg | 133.322368 |
| Kilopascal | kPa | 1,000 |
| Pound per square inch | psi | 6,894.757293 |
| Bar | bar | 100,000 |
| Atmosphere | atm | 101,325 |
Bar and millibar are handy because 1 bar equals exactly 100,000 Pa and 1 mbar equals 100 Pa. The millibar also matches the hectopascal (hPa) that meteorologists use. The standard atmosphere (atm) is defined as 101,325 Pa, very close to sea-level pressure.
Worked example
A car manual asks you to inflate the tires 1 bar above the usual setting. How much is that in other units?
- In pascals: 1 × 100,000 = 100,000 Pa (100 kPa).
- In psi: 100,000 ÷ 6,894.757293 ≈ 14.5038 psi.
- In atmospheres: 100,000 ÷ 101,325 ≈ 0.986923 atm.
- In mmHg: 100,000 ÷ 133.322368 ≈ 750.062 mmHg.
So 1 bar is about 14.5 psi — the value you would read on a gas-station gauge.
Bar, atm and psi: how do they differ?
People mix them up because all three sit near atmospheric pressure. The bar is a round metric unit (100,000 Pa). The atmosphere is 101,325 Pa, about 1.3 % more than a bar. The psi is imperial: 1 psi ≈ 6,895 Pa, so 1 atm equals 14.6959 psi and 1 bar equals 14.5038 psi. That is why a European manual in bar and a U.S. gauge in psi report different numbers for the same tire.
Frequently asked questions
How many psi are in 1 bar?
One bar equals 14.5038 psi. That is the conversion you need when the car manual is in bar but your gauge reads psi. Going the other way, 1 psi is 0.0689476 bar.
Is 1 atmosphere the same as 1 bar?
Almost, but not quite. A standard atmosphere is 101,325 Pa and a bar is 100,000 Pa, so 1 atm equals 1.01325 bar — the atmosphere is about 1.3 % larger.
Why is blood pressure measured in mmHg?
Because of old mercury manometers: pressure was read from the height of a mercury column. A reading of 120 mmHg equals roughly 15,999 Pa, or 0.160 bar above atmospheric pressure.
Are millibars and hectopascals the same?
Yes. 1 mbar = 100 Pa = 1 hPa. So an atmospheric pressure of 1013 mbar and one of 1013 hPa are identical; meteorologists use the two terms interchangeably.