Free Pressure Converter
Convert between PSI, bar, atm, Pascal, kPa, mmHg, torr, and inHg. Instant pressure unit conversion for engineering, weather, and science.
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1 Atmospheres (atm) =
Formula
Converted Value = Input Value × (Source Unit in Pa) ÷ (Target Unit in Pa)How to Convert Pressure Units
Pressure conversion normalizes all values to Pascals (the SI unit), then converts to your target unit. Pressure measures force per unit area and is critical in engineering, meteorology, medicine, and everyday applications like tire inflation.
Pressure Units Explained
- Pascal (Pa) — SI unit. 1 Pa = 1 N/m². Very small; atmospheric pressure is ~101,325 Pa.
- Kilopascal (kPa) — 1,000 Pa. Used for tire pressure in many countries and in engineering.
- Bar — 100,000 Pa. Close to 1 atmosphere. Common in European tire gauges and industrial applications.
- Atmosphere (atm) — standard atmospheric pressure at sea level. 1 atm = 101,325 Pa.
- PSI — pounds per square inch. Standard in the US for tire pressure, hydraulics, and air compressors.
- mmHg — millimeters of mercury. Used for blood pressure readings (e.g., 120/80 mmHg).
- Torr — essentially equal to mmHg. Used in vacuum science and physics.
- inHg — inches of mercury. Used in US weather reports for barometric pressure.
Common Pressure References
- Car tire: 30-35 PSI (207-241 kPa)
- Normal blood pressure: 120/80 mmHg
- Bike tire: 80-130 PSI (551-896 kPa)
- Scuba tank: ~3,000 PSI (207 bar)
- Atmospheric pressure (sea level): 14.7 PSI (101.3 kPa)
Frequently Asked Questions
How do I convert PSI to bar?
Divide PSI by 14.5038 to get bar. For example, 30 PSI ÷ 14.5038 ≈ 2.07 bar. Standard tire pressure of 32 PSI equals about 2.21 bar.
What is standard atmospheric pressure?
Standard atmospheric pressure at sea level is 1 atm = 101,325 Pa = 14.696 PSI = 1.01325 bar = 760 mmHg = 29.92 inHg.
What is the difference between mmHg and torr?
They are nearly identical. 1 torr = 1 mmHg for most practical purposes. Both are defined as 1/760 of an atmosphere. The torr is named after Evangelista Torricelli.
What pressure unit is used for tire pressure?
In the US, tire pressure is measured in PSI (pounds per square inch). Most cars recommend 30-35 PSI. In Europe and most other countries, bar or kPa are used instead.
What is a Pascal?
A Pascal (Pa) is the SI unit of pressure, equal to 1 newton per square meter. It's a very small unit — atmospheric pressure is about 101,325 Pa, which is why kilopascals (kPa) are more commonly used.