Pressure Converter — Calculator

About pressure conversions

Pressure is force spread over an area, measured in pascals — one newton per square meter. A pascal is a very small quantity: the weight of a sheet of paper resting on a table amounts to only a few pascals, which is why everyday pressures are quoted in kilopascals, bar or psi instead.

Three units dominate in practice and sit close enough together to cause confusion. One bar is exactly 100,000 Pa, one atmosphere is exactly 101,325 Pa, and one psi is 6,894.757293168 Pa. Weather reporting uses millibars or hectopascals, which are the same size; tyres use kPa, bar or psi; blood pressure is still measured in millimeters of mercury.

Tyre pressure (kPa, bar or psi).
Weather and altitude (millibars, hectopascals, inches of mercury).
Blood pressure (millimeters of mercury).
Industrial gas and hydraulics (bar, megapascals).

Reading the answers. Bar, atmosphere and psi are exact definitions. Gauges and weather stations round heavily, so treat the last digit as indicative rather than precise.

The units in this converter

What each unit is and where it is normally used. Everything here is converted through the pascals.

Pascals (Pa): The pascal is the SI unit of pressure: one newton per square meter. It is used in science and engineering, usually as kilopascals or megapascals.
Kilopascals (kPa): A kilopascal is 1,000 pascals. It is the unit for tyre pressure in metric countries, and is used for gas and weather pressures.
Megapascals (MPa): A megapascal is 1,000 kilopascals, or one million pascals. It is used for concrete strength, where structural concrete is typically specified between 20 and 40 MPa.
Bar (bar): One bar is exactly 100,000 pascals, slightly less than one atmosphere. It is used for tyre pressure, industrial gases and weather charts.
Millibar (mbar): A millibar is 100 pascals, identical to the hectopascal used in weather reports. Average sea-level pressure is about 1,013 millibars.
Atmospheres (atm): One atmosphere is exactly 101,325 pascals, the average air pressure at sea level. It is used for gas calculations and diving tables.
Pounds per square inch (psi): One psi (pound per square inch) is 6,894.757293168 pascals. It is the tyre-pressure and hydraulic unit in the United States and the UK.
Millimeters of mercury (mmHg): One millimeter of mercury is 133.322387415 pascals. It is still used for blood-pressure readings, where 120/80 mmHg is the familiar healthy range.
Inches of mercury (inHg): One inch of mercury is 3,386.389 pascals. It is used for barometric pressure and altimeter settings in aviation in the United States.

Popular conversions

Bar to Pounds per square inch Pounds per square inch to Bar Kilopascals to Pounds per square inch Pounds per square inch to Kilopascals Atmospheres to Pounds per square inch Millimeters of mercury to Kilopascals Bar to Atmospheres

Convert from any pressure unit

Each unit has its own page with every other unit in the dimension, the exact factor for each, and worked values.

Pascals converterPa to 8 other pressure units Kilopascals converterkPa to 8 other pressure units Megapascals converterMPa to 8 other pressure units Bar converterbar to 8 other pressure units Millibar convertermbar to 8 other pressure units Atmospheres converteratm to 8 other pressure units Pounds per square inch converterpsi to 8 other pressure units Millimeters of mercury convertermmHg to 8 other pressure units Inches of mercury converterinHg to 8 other pressure units

Frequently asked questions

How many psi are in a bar?

One bar equals about 14.5 psi.

How do I convert psi to kPa?

Multiply psi by about 6.895 to get kilopascals.

What is standard atmospheric pressure?

Standard atmospheric pressure is 1 atm, which equals 101,325 pascals, about 14.7 psi, or 760 mmHg.

All pressure conversions

Every pressure conversion on Calculator, listed in full.