Pressure Converter

Convert PSI, Bar, Pascal, and Atmosphere

Last updated: 10/8/2026

Data sources:NIST Special Publication 811, Appendix B: Conversion factors

Enter a pressure in psi, bar, pascals, kilopascals, or standard atmospheres and the converter lists the same pressure in all five units. Tyre placards, compressor gauges, dive tables, and weather reports each favour a different unit, and the numbers differ by enough that a mistake is obvious once you know the anchors: 1 bar is almost exactly 1 atmosphere and about 14.5 psi.

Calculator Inputs

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The converter does not distinguish gauge from absolute pressure and does not correct for altitude or temperature.

How It Works

Pressure is force per unit area. The value is first converted to pascals (newtons per square metre): 1 kPa = 1,000 Pa; 1 bar = 100,000 Pa; 1 atm = 101,325 Pa (exact definition); 1 psi = 4.448222 N ÷ (0.0254 m)² = 6,894.76 Pa. Reversed: 1 bar = 14.5038 psi = 0.98692 atm, and 1 atm = 14.6959 psi = 1.01325 bar.

Gauge pressure versus absolute pressure

Most gauges read zero when open to the air, so they show pressure above atmospheric (gauge pressure, sometimes written psig or bar(g)). Absolute pressure adds the roughly 1 atm of air pressure on top. A tyre at 32 psi gauge is at about 46.7 psi absolute at sea level. This converter changes units only; it does not add or subtract atmospheric pressure, so convert gauge to gauge or absolute to absolute.

Worked example

A tyre placard reads 240 kPa; what is that in psi and bar?

Pascals:240 kPa × 1,000= 240,000 Pa

psi:240,000 Pa ÷ 6,894.76 Pa/psi= 34.81 psi

bar:240,000 Pa ÷ 100,000 Pa/bar= 2.400 bar

atm:240,000 Pa ÷ 101,325 Pa/atm= 2.369 atm

Tyre gauges are usually marked in whole psi, so you would inflate to 35 psi.

Tips & Best Practices

•psi is standard for tyre and compressor pressure in the US; kPa and bar appear on the same placards in most other markets.
•Weather pressure is quoted in hectopascals (hPa) or millibars; 1 hPa = 1 mbar = 100 Pa, so 1013.25 hPa is exactly 1 atm.
•Divers use bar for tank pressure (a full 200 bar tank is about 2,900 psi) and each 10 m of seawater adds roughly 1 bar.

Frequently Asked Questions

Is 1 bar the same as 1 atmosphere?

Close but not identical. 1 bar is defined as exactly 100,000 Pa; 1 standard atmosphere is 101,325 Pa, so 1 atm = 1.01325 bar and 1 bar = 0.98692 atm. For tyre pressure the difference is negligible; for scientific work use the exact values.

How many psi is 1 bar?

14.5038 psi. A quick mental rule is bar × 14.5, or psi ÷ 14.5.

What is the difference between kPa and MPa?

A megapascal is 1,000 kPa or 1,000,000 Pa. Hydraulic systems and material strengths are usually quoted in MPa; 1 MPa = 10 bar = 145.04 psi. To convert MPa with this tool, enter the value × 1,000 as kPa.