What is a Pressure Unit Converter?
The pressure unit converter switches between Pa, kPa, MPa, bar, atm, psi, kgf/cm², and mmHg — used for equipment specs, tire pressure, and piping design.
How it's calculated
1 bar = 100,000 Pa ≈ 14.5 psi
1 atm = 101,325 Pa = 760 mmHg
1 kgf/cm² ≈ 0.98 bar
Why bar and kgf/cm² are almost interchangeable
1 kgf/cm² is 'the pressure of 1 kg resting on 1 cm²,' and 1 bar was defined to be roughly Earth's atmospheric pressure — these two definitions happen to land within about 2% of each other. That is why older equipment drawings in kgf/cm² and newer specs in bar are often read as roughly interchangeable on the shop floor, even though precise engineering calculations should still convert properly.
Good to know
- Gauge pressure and absolute pressure are different. A gauge reading zero still has atmospheric pressure acting on it — which is why compressor and vacuum specs distinguish 'barg' (gauge) from 'bara' (absolute).
- Blood pressure is measured in mmHg because of the historical mercury column manometer — the unit stuck around even though mercury devices are rarely used today.
- Tire pressure is shown in bar/kPa in most of the world and psi in the US — 35 psi is roughly 2.4 bar or 240 kPa.
- The pascal (Pa) is a tiny unit — about the pressure a single sheet of paper exerts — so practical use almost always defaults to kPa or MPa.
- Atmospheric pressure drops with altitude. At high elevation it can fall to roughly 80% of sea level, which is why water boils at a lower temperature and rice can come out undercooked in mountain kitchens.
Frequently asked questions
Q. How many psi is 1 bar?
About 14.5 psi. Conversely, 1 psi is about 0.069 bar.
Q. Can I treat kgf/cm² and bar as equal?
They differ by about 2%, which is often treated as negligible in the field, but should be converted precisely for engineering calculations.
Q. What's the difference between barg and bara?
Barg is gauge pressure (zero = atmospheric), bara is absolute pressure (zero = full vacuum). The two differ by about 1 bar.