Pressure Converter
Convert psi, bar, kPa, atmospheres, and mmHg with exact factors.
What it does
Tire gauges read psi while many manuals and pumps read bar, and weather plus medicine add kilopascals, atmospheres, and millimeters of mercury. All five describe force per area with different reference points.
The tool above converts between psi, bar, kPa, atm, and mmHg. Enter the value, pick both ends, and read every equivalent below the answer.
The bar sits closest to everyday air: one bar is 100 kilopascals, just under one atmosphere at sea level. Pounds per square inch runs finer, near 6.9 kPa each, which suits the small numbers on tire sidewalls.
Tire pressure is a cold measurement. Driving warms air and raises readings by several psi, so morning checks before rolling give the honest number that the door sticker means.
How to use
- Enter the pressure number.
- Pick the unit it is written in and the unit you want.
- Read the converted line for the answer.
- For tires, compare against the door sticker value in matching units.
Formula
- 6.89476
- Kilopascals in one psi, exact from inch and pound definitions.
- 100
- Kilopascals in one bar, exact by definition.
- 101.325
- Kilopascals in one standard atmosphere.
- 0.133322
- Kilopascals in one mmHg, from mercury density.
Gauge pressure reads above atmosphere while absolute adds it back. Tire and pump numbers are gauge; weather and physics equations usually want absolute.
Worked example
Example: 32 psi to bar
Value 32, from psi, to bar. A common car tire pressure.
- To kPa: 32 x 6.89476 = 220.6323.
- To bar: 220.6323 / 100 = 2.2063 bar.
- Result: 32 psi = 2.2063 bar.
- In kPa: 220.6 kPa, near the 220 door sticker many cars show.
Reference table
| Use | Typical | In bar |
|---|---|---|
| Road bike tire | 80-130 psi | 5.5-9.0 bar |
| Car tire | 30-35 psi | 2.1-2.4 bar |
| Basketball | 7.5-8.5 psi | 0.52-0.59 bar |
| Home water | 40-80 psi | 2.8-5.5 bar |
| Sea level air | 14.7 psi | 1.01 bar |
Limits
- Gauge units assumed. Absolute readings add one atmosphere.
- Altitude shifts gauge zero slightly; pumps self correct.
- Temperature moves tire readings a few psi either way.
- Medical mmHg follows its own device calibration.
Common mistakes
- Inflating to the sidewall maximum instead of the door sticker.
- Checking hot tires and bleeding to the cold number.
- Mixing bar and psi on pump presets.
- Ignoring the spare, which leaks down unnoticed.
- Trusting gas station gauges without a personal check.
Try it yourself
Quick checks. Answers sit tucked under each question.
2.5 bar in psi?
2.5 x 100 / 6.89476 = 36.26 psi.
101.3 kPa in atm?
101.3 / 101.325 = 1.0 atm, standard air.
Questions
What psi should car tires be?
Usually 30 to 35 psi cold, printed on the driver door sticker, not the tire sidewall.
How much is 1 bar in psi?
About 14.5038 psi. Two bar is 29 psi.
Why check tires cold?
Heat raises pressure 3 to 5 psi, hiding underinflation. Morning readings match the sticker.
Gauge or absolute?
Tire numbers are gauge, above atmosphere. Add 14.7 psi for absolute.
What is mmHg used for?
Blood pressure and vacuum work. Normal arterial reads near 120 over 80 mmHg.
Does altitude change tire pressure?
Slightly. Gauges reference local air, so readings hold while absolute shifts.