Pa · kPa · MPa · bar · atm · PSI · Torr

Free Pressure Converter

Convert pressure units instantly — bar, PSI, Pascal, atmosphere, Torr, kPa, MPa. Type into any field and all others update. Free, symmetrical, no sign-up.

Formula & standards

Exact Conversion Formula & Multipliers

Standard atmospheric pressure is fixed at 1 atm = 101,325 pascals exactly, while 1 bar = 100,000 pascals exactly (chosen as a round metric number close to 1 atm for convenience). From these, 1 psi = 6,894.757293168 Pa and 1 mmHg = 133.322387415 Pa (the conventional value, based on mercury's density at 0°C under standard gravity). This converter keeps atm, bar, and their derived units separate rather than treating them as interchangeable round numbers.

In practice

Practical Real-World Scenarios

Automotive and cycling: tire pressure is specified in psi in the US and UK but in bar or kPa in most of Europe and Asia, a frequent point of confusion when using a foreign pump gauge.
Meteorology: barometric pressure is reported in millibars (hectopascals) internationally but in inches of mercury on US weather broadcasts.
Medicine and diving: blood pressure is measured in mmHg worldwide, while scuba diving depth-pressure calculations typically use bar or atm.

Background

Historical & Technical Background

The 'standard atmosphere' was originally defined by Evangelista Torricelli's 17th-century mercury barometer experiments, which measured air pressure by the height of a mercury column it could support at sea level. The bar, introduced in the early 20th century by meteorologist William Napier Shaw, was deliberately chosen close to but distinct from the atmosphere for cleaner metric arithmetic in weather reporting, which is why 1 bar and 1 atm differ by only about 1.3%.

✓ Verified against BIPM SI Brochure definitions and NIST Special Publication 811 conversion factors

Precision & Accuracy Statement

Every conversion factor used on this page is checked against internationally recognized reference standards — BIPM SI Brochure definitions and NIST Special Publication 811 conversion factors — rather than approximated or rounded for display. Where a constant is fixed by international definition (such as 1 inch = 2.54 cm, or standard gravity = 9.80665 m/s²), we use the exact defined value. Where a figure is a practical industry convention rather than a physical constant, that distinction is stated explicitly above so results are never presented with false precision.

Why symmetrical conversion?

How This Converter Works

Pressure is measured in different units across industries — PSI in the US, bar in Europe, Pascal in science, atmosphere in meteorology. Our converter handles all 8 units simultaneously with symmetrical updating.

Bar to PSI tire pressure guide →

Quick reference

Common Conversions

Pascal (Pa)	Bar	PSI	Atmosphere (atm)
1 Pa	0.00001 bar	0.000145 PSI	0.00000987 atm
100,000 Pa	1.0 bar	14.504 PSI	0.9869 atm
101,325 Pa	1.01325 bar	14.696 PSI	1.0 atm
6,894.76 Pa	0.06895 bar	1.0 PSI	0.06805 atm
220,632 Pa	2.2063 bar	32 PSI	2.177 atm

FAQ

Frequently Asked Questions

1How do I convert bar to PSI?

Multiply bar by 14.5038. So 2.2 bar × 14.5038 = 31.9 PSI. For a quick estimate, multiply by 14.5. This is essential for tire pressure conversion between European and US standards.

2What is the difference between 1 bar and 1 atmosphere?

They are very close but not identical. 1 atmosphere = 1.01325 bar. For most everyday purposes they are treated as equivalent, but in precision science the difference matters.

3What pressure unit is used for tire inflation?

PSI (pounds per square inch) in the US, bar in Europe, and kPa in some markets. Most car tires require 30–35 PSI (2.1–2.4 bar) cold pressure.

4What is a Pascal?

The Pascal (Pa) is the SI base unit of pressure, equal to one Newton per square meter (1 N/m²). It is a very small unit — 1 bar = 100,000 Pa — so kilopascals (kPa) and megapascals (MPa) are commonly used.

Related converters