Pressure Converter

1. Enter the value you want to convert.
2. Choose the from unit.
3. Choose the to unit.
4. Read the result and the conversion rate.

Here is what each result means:

Pressure is force spread over an area, and it is measured in many units because different fields settled on different standards. Weather reports use hectopascals or millibars, tyre pressure uses psi or bar, and science uses pascals. Converting between them is a common need when a figure is quoted in a unit you are not used to.

The SI unit is the pascal, one newton per square meter. It is small, so everyday pressures are large numbers: normal atmospheric pressure is about 101,325 pascals. That is why kilopascals, bar and atmospheres, which are larger units, are often more convenient for real-world pressures.

This converter bridges every unit through the pascal. It multiplies your value by the number of pascals in its unit, then divides by the number of pascals in the target unit. Because each unit has a fixed value in pascals, the conversions are exact ratios that never change.

It converts through the pascal, the SI unit of pressure.

1. Your value is multiplied by its unit's value in pascals.
2. That gives the pressure in pascals, the common base.
3. Dividing by the target unit's value in pascals gives the result.

For the physics of pressure, see the pressure calculator and the force calculator.

Convert 1 atmosphere to psi.

Result: 1 atm is 101,325 pascals, and dividing by 6,894.76 pascals per psi gives about 14.7 psi. In kilopascals the same pressure is 101.325 kPa.

Every unit has a fixed value in pascals.

A bar is very close to one atmosphere, which is why weather charts in millibars are easy to read: 1013 millibars is roughly normal sea-level pressure. Psi is common for tyres and gauges, especially in the United States.

Different fields favour different units.

Knowing which unit a field prefers helps you sense-check a figure. A tyre at 32 psi, a storm at 980 millibars and a lab at 1 atmosphere are all everyday pressures written in the unit each field finds most natural.

The Two Units

The ratio between the from-unit and to-unit sets the result; each has a fixed value in pascals.

Absolute vs Gauge

Gauge pressure is measured above the atmosphere; absolute includes it. This converter treats the numbers as given.

Temperature for MmHg

Millimetres of mercury depend slightly on temperature; the standard value at 0 degrees Celsius is used.

Everyday Tasks

Convert a tyre pressure from psi to bar, or a weather reading between millibars and kilopascals.

Science and Engineering

Move between pascals and other units in calculations.

Travel and Imports

Read a gauge quoted in a unit you do not normally use.

1. Confusing Bar and Atmosphere

They are close but not equal: 1 atm is 1.01325 bar, not exactly 1 bar.

2. Mixing Gauge and Absolute

A tyre gauge reads above atmospheric pressure, so gauge and absolute figures differ by about 1 atm.

3. Wrong Direction

Check which unit is the from and which is the to; swapping them inverts the result.

4. Forgetting the Scale of the Pascal

The pascal is small, so everyday pressures are tens or hundreds of thousands of pascals.

5. Treating MmHg as Exact

Millimetres of mercury vary slightly with temperature; a standard value is used here.

Conversions use fixed, exact factors relative to the pascal.

About 14.7 psi. One atmosphere is 101,325 pascals, and dividing by 6,894.76 pascals per psi gives roughly 14.7 psi.

Multiply bar by 14.5038, since 1 bar is 100,000 pascals and 1 psi is 6,894.76 pascals. So 2 bar is about 29 psi.

The pascal, one newton per square meter. It is small, so everyday pressures are large numbers, which is why bar and atmospheres are often used.

Almost, but not exactly. One atmosphere is 1.01325 bar, so a bar is slightly less than an atmosphere.

Multiply kilopascals by 0.145038. For example, 100 kPa is about 14.5 psi. This converter does it for you in both directions.

Millimetres of mercury, also called torr, a unit from measuring pressure with a mercury column. One atmosphere is 760 mmHg. It is common in medicine.

Gauge pressure is measured above atmospheric pressure; absolute pressure includes the atmosphere. They differ by about one atmosphere. This tool treats the number as given.

Different fields adopted different standards over time. Weather uses millibars, tyres use psi, and science uses pascals, so converting between them is often needed.

No. The calculation runs in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only on this device.

• Pascal (unit) (Wikipedia).
• Pressure (Wikipedia).
• Bar (unit) (Wikipedia).