🔩 Pressure Converter
Convert between PSI, bar, atmospheres, pascals, kilopascals, millimeters of mercury, torr, and inches of mercury.
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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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Related Guides
How to Convert PSI to kPa
Learn the exact formula for converting PSI to kPa and back. Includes real-world examples from tire pressure to industrial specifications, a quick-reference table, and common FAQs.
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Pressure Units Explained: PSI, kPa, Bar, atm, and mmHg
Understand every common pressure unit — PSI, kilopascal, bar, atmosphere, and mmHg. Learn the conversion factors, where each unit is used, and how to move between them.
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What Is PSI? Pound-Force Per Square Inch Explained
PSI (pounds per square inch) is the US standard unit of pressure. Learn what PSI measures, how it compares to kPa and bar, and where you encounter it in everyday life.
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What Is kPa? Kilopascal Explained
kPa (kilopascal) is the metric unit of pressure used globally. Learn what a kilopascal measures, how it compares to PSI and bar, and where it appears in everyday life.
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What Is Bar? The Bar Unit of Pressure Explained
Bar is a metric unit of pressure close to one standard atmosphere. Learn how bar compares to PSI and kPa, where it is used in industry, scuba diving, and everyday applications.
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Atmospheric Pressure Explained: What It Is and Why It Changes
Atmospheric pressure is the weight of the air column above you. Learn what determines atmospheric pressure, why it changes with altitude and weather, and how it is measured in PSI, kPa, bar, and mmHg.
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Reference Handbooks
Sources
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How we source and verify conversion factors.
Reference Library
Tables, charts, and authoritative reference data.
Reference Charts
PSI to kPa Conversion Chart
Quick-reference chart converting PSI (pounds per square inch) to kilopascals (kPa). Covers 1–250 PSI — for tire pressure, industrial systems, and medical equipment.
kPa to PSI Conversion Chart
Quick-reference chart converting kilopascals (kPa) to PSI (pounds per square inch). Covers 1–1,750 kPa — for tire pressure, weather data, industrial, and medical applications.
Bar to PSI Conversion Chart
Quick-reference chart converting bar to PSI. Covers 0.1–700 bar — for compressed air, hydraulic systems, diving equipment, and industrial applications.
PSI to Bar Conversion Chart
Quick-reference chart converting PSI to bar. Covers 1–5,000 PSI — for tires, compressed air systems, hydraulics, and industrial pressure equipment.
Atmospheres (atm) to PSI Conversion Chart
Reference chart converting standard atmospheres (atm) to PSI. Covers 0.1–1,000 atm — for diving, scientific, industrial, and engineering pressure calculations.
PSI to Atmospheres (atm) Conversion Chart
Reference chart converting PSI to standard atmospheres (atm). Covers 1–10,000 PSI — for engineering, diving, autoclave, and scientific pressure applications.
All Converters
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.