Pressure Converter
Convert PSI, bar, kPa, atmospheres, and mmHg.
Conversion sheet
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Tire pressure in PSI, weather in millibars or atmospheres, lab and industrial specs in kilopascals — pressure is quoted differently across cars, weather, diving, and engineering. This converter pivots every unit through the pascal so they all reconcile.
How it works
Pressure values convert through pascals as the base unit.
The pascal is the SI base, but it's tiny — one pascal is about the pressure of a dollar bill lying flat. That's why everyday work uses kilopascals, bar (100,000 Pa), or PSI (6894.76 Pa).
One atmosphere (101,325 Pa) is standard sea-level air pressure, close to but not exactly 1 bar. Millimeters of mercury (mmHg, 133.322 Pa) survive in blood-pressure readings and barometers.
Result = (value × pascals-per-source-unit) ÷ pascals-per-target-unit.
Worked examples
Convert 32 PSI of tire pressure to bar. → 2.21 bar
32 × 6894.757 = 220,632 Pa, divided by 100,000 = 2.206 bar.
Convert 1 atmosphere to PSI. → 14.70 PSI
101,325 Pa ÷ 6894.757 Pa per PSI = 14.70 PSI.
Tips & gotchas
- Tire gauges read 'gauge' pressure (above atmosphere), while absolute pressure adds the surrounding atmosphere. For everyday tire and weather work, treat the readings as gauge.
- A handy anchor: standard atmospheric pressure is about 14.7 PSI, 1.013 bar, or 101.3 kPa — all the same thing.
- 1 bar is almost exactly 1 atmosphere, off by about 1.3%. For rough work they're interchangeable; for precise engineering, use the exact factor.
- Blood pressure stays in mmHg by convention. A 120/80 reading is about 16.0/10.7 kPa, but medicine never uses the metric form.
FAQ
Is 1 bar the same as 1 atmosphere?
Very nearly. One bar is 100,000 Pa and one atmosphere is 101,325 Pa, so a bar is about 1.3% less. Close enough for tires; exact lab work uses the precise factors.
What's a typical car tire pressure in different units?
Around 32 PSI, which is about 2.21 bar or 221 kPa. Always follow the figure on the door-jamb sticker, not the maximum printed on the tire.
Why is pressure measured in millimeters of mercury?
Early barometers used a column of mercury, and the height of that column in millimeters became the unit. It persists in medicine (blood pressure) and meteorology.
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