What is the Pressure Conversion Calculator?
This calculator converts a pressure value between common units: Pascal (Pa), kilopascal (kPa), bar, pound-force per square inch (psi), standard atmosphere (atm), and millimetre of mercury (mmHg, also called Torr). Pressure is force per unit area, and because different industries and countries use different units, quick conversion is essential in engineering, meteorology, diving, automotive, and HVAC work. This tool is universal — the SI unit and conversion factors are international standards.
How to use it
Enter the numeric value you want to convert, choose the unit you are converting from, and choose the unit you are converting to. The result appears instantly along with the equivalent value in Pascals so you can sanity-check the conversion.
The formula explained
Every conversion uses Pascals as the common base. Each unit has a fixed factor equal to how many Pascals it represents: \(1\,\text{Pa} = 1\), \(1\,\text{kPa} = 1{,}000\), \(1\,\text{bar} = 100{,}000\), \(1\,\text{psi} = 6{,}894.757\,\text{Pa}\), \(1\,\text{atm} = 101{,}325\,\text{Pa}\), and \(1\,\text{mmHg} = 133.322\,\text{Pa}\). To convert, the value is first multiplied by its source factor to get Pascals, then divided by the target factor: $$\text{result} = \frac{\text{value} \times \text{factor}_{\text{from}}}{\text{factor}_{\text{to}}}$$
Worked example
Convert 2 bar to psi. First to Pascals: $$2 \times 100{,}000 = 200{,}000\,\text{Pa}$$ Then divide by the psi factor: $$200{,}000 \div 6{,}894.757 \approx 29.0075\,\text{psi}$$ So 2 bar is roughly 29 psi — close to typical car tyre pressures.
FAQ
Why is 1 atm = 101,325 Pa? That is the defined value of the standard atmosphere at sea level, fixed by international agreement.
Is bar the same as atm? Almost, but not exactly. \(1\,\text{bar} = 100{,}000\,\text{Pa}\) while \(1\,\text{atm} = 101{,}325\,\text{Pa}\), so \(1\,\text{atm} \approx 1.01325\,\text{bar}\).
What is mmHg used for? Millimetres of mercury are common in medicine (blood pressure) and barometric measurements; \(760\,\text{mmHg} \approx 1\,\text{atm}\).
