π Pressure Converter
PSI, bar, kPa, atm, mmHg, inHg with live results and tire presets.
All pressure units
How to Use This Pressure Converter
Enter a pressure, pick its unit, and see every equivalent instantly. The presets jump straight to common tire pressures. Whether you are inflating tires, reading a weather map, or setting up a compressor, this tool speaks every pressure unit.
Type the pressure value, or click a tire preset.
Choose the starting unit from the dropdown.
Read all converted units in the results panel.
Pressure Units Explained
PSI (pounds per square inch) is the US standard for tires, tools, and plumbing. Bar is the metric workshop standard, close to one atmosphere, and the unit on most European tire gauges. Kilopascals are the SI unit used in science and on many digital gauges. Atmospheres measure against sea-level air pressure, handy for diving and vacuum work.
mmHg (millimeters of mercury, or torr) is the medical and barometric standard: blood pressure 120/80 is measured in mmHg. inHg (inches of mercury) is what US weather reports use: standard sea-level pressure is 29.92 inHg. PSF (pounds per square foot) appears in structural engineering for wind and snow loads.
Key Conversion Factors
Worked Example
Your car's door sticker says 2.2 bar but your gauge reads PSI. Convert: 2.2 Γ 14.5038 = 31.9 PSI, so inflate to about 32 PSI. A weather report of 29.92 inHg equals 101.325 kPa or 1 atm, the definition of standard sea-level pressure.
Tire Pressure Tips
Always inflate to the vehicle manufacturer's spec (on the door jamb sticker), not the maximum printed on the tire sidewall. Check pressures cold, before driving, since heat raises readings by 1 to 2 PSI. Underinflation by just 5 PSI increases tire wear and fuel consumption noticeably, while overinflation harshens the ride and shrinks the contact patch.
Gauge vs Absolute Pressure
Most gauges read zero at atmospheric pressure, showing gauge pressure: your 32 PSI tire actually holds about 46.7 PSI absolute (32 + 14.7). Scientific and vacuum work uses absolute pressure, measured from a perfect vacuum. Weather reports use absolute station pressure adjusted to sea level. When a specification just says PSI without qualifying, it almost always means gauge in automotive and tool contexts, and absolute in physics contexts, so check before converting critical values.
Frequently Asked Questions
How many PSI are in one bar?
14.5038 PSI. So a 2.2 bar tire pressure equals about 31.9 PSI. Bar is the metric workshop standard, roughly equal to one atmosphere.
What is normal tire pressure in PSI?
Most passenger cars specify 32 to 35 PSI (check the door jamb sticker, not the tire sidewall). Road bikes run 65 to 100 PSI, mountain bikes 25 to 35 PSI.
How do I convert PSI to kPa?
Multiply PSI by 6.89476. So 32 PSI equals about 220.6 kPa. Many digital gauges let you switch units directly.
What does mmHg measure?
Millimeters of mercury, the medical and barometric standard. Blood pressure (120/80), vacuum gauges, and some barometers all use mmHg. Standard atmosphere is 760 mmHg.
Is bar the same as atm?
Nearly but not exactly. One bar is 100 kPa; one standard atmosphere is 101.325 kPa. They differ by about 1.3 percent, which matters in science but rarely in the garage.