🔩 Pressure Converter
Convert between PSI, bar, atmospheres, pascals, kilopascals, millimeters of mercury, torr, and inches of mercury.
Enter a value above to see the result
Common Pressure Conversions
| Input | Unit | Result | Unit |
|---|---|---|---|
| 1 | Atmosphere | 101.325 | Kilopascal |
| 1 | Bar | 14.503774 | Pounds per Square Inch |
| 14.696 | Pounds per Square Inch | 1.0000035 | Atmosphere |
| 1 | Atmosphere | 759.99989 | Millimeter of Mercury |
| 760 | Millimeter of Mercury | 101325.01 | Pascal |
| 100 | Kilopascal | 14.503774 | Pounds per Square Inch |
Popular Conversions
Formula Reference
Standard atmosphere: 1 atm = 101,325 Pa = 101.325 kPa ≈ 14.696 psi ≈ 1.01325 bar 1 bar = 100,000 Pa • 1 psi = 6,894.757 Pa • 1 mmHg ≈ 133.322 Pa
About Pressure Conversions
Pressure is the force applied per unit area. The SI unit is the pascal (Pa), defined as one newton per square meter. Because a pascal is extremely small, engineering and everyday use favors kilopascals (kPa), megapascals (MPa), and bar. Weather forecasts use hectopascals (hPa) — equivalent to millibars — with standard sea-level atmospheric pressure sitting at about 1,013 hPa.
In the United States, pounds per square inch (PSI) dominates industrial and automotive applications. Tire pressure is expressed in PSI, hydraulic systems are rated in PSI, and plumbing codes use PSI for pipe pressure ratings. The standard atmosphere (atm) is an older unit tied to mean sea-level pressure: 1 atm = 101,325 Pa. Bar is close to this — 1 bar = 100,000 Pa — and is widely used in European industry.
Medical and laboratory work often uses millimeters of mercury (mmHg) or its equivalent torr. Blood pressure is still universally reported in mmHg: a reading of 120/80 means 120 mmHg systolic over 80 mmHg diastolic. The torr is defined to be exactly 1/760 of a standard atmosphere, and at normal conditions is so close to 1 mmHg that the two are used interchangeably in most practical contexts.
Frequently Asked Questions
What is standard atmospheric pressure?
Standard atmospheric pressure is defined as exactly 101,325 pascals (101.325 kPa), equal to 1 atm, approximately 1.01325 bar, 14.696 psi, or 760 mmHg. This is the approximate mean sea-level air pressure and is used as a reference point for many scientific and engineering calculations.
What PSI should my car tires be?
Most passenger cars recommend between 30 and 35 PSI (about 207–241 kPa) for standard tires. The correct pressure is printed on a sticker inside the driver's door jamb — not the tire sidewall, which shows the maximum pressure. Always check tires when cold, as pressure increases when tires heat up during driving.
What is the difference between gauge pressure and absolute pressure?
Absolute pressure is measured relative to a perfect vacuum (zero pressure). Gauge pressure is measured relative to local atmospheric pressure. When you inflate a tire to '32 PSI', that is gauge pressure — the actual absolute pressure inside is approximately 32 + 14.7 = 46.7 PSI. Most everyday pressure readings (tires, blood pressure, plumbing) use gauge pressure.
Why is blood pressure measured in mmHg?
Blood pressure has been measured in millimeters of mercury (mmHg) since the 19th century, when mercury sphygmomanometers were the standard instrument. A reading of 120 mmHg means the pressure is high enough to push a column of mercury 120 mm tall. Despite mercury instruments being largely replaced by digital devices, the mmHg unit persists as the universal medical standard.
What is the difference between bar and atmosphere?
One bar is exactly 100,000 Pa, while one standard atmosphere is 101,325 Pa — so they are close but not equal. Bar is convenient for metric calculations because it rounds neatly. Atmosphere reflects actual mean sea-level air pressure. In weather, 1 bar ≈ 1000 hPa, which is slightly below standard atmospheric pressure.
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All conversion results are provided for general informational purposes only. Our formulas use internationally recognized conversion factors; however, rounding may affect precision. Do not rely on these results for professional, medical, legal, or engineering decisions without independent verification. Read our full disclaimer.