Question 1

What is atmospheric pressure in different units?

Accepted Answer

Standard atmospheric pressure (1 atm) equals 101,325 Pa, 1.01325 bar, 14.696 psi, 760 mmHg, and 760 Torr. These are all equivalent values for normal sea-level atmospheric pressure.

Question 2

What is the difference between bar and PSI?

Accepted Answer

Bar is a metric unit approximately equal to atmospheric pressure at sea level. PSI (pounds per square inch) is an imperial unit. 1 bar ≈ 14.504 PSI. Bar is common in Europe; PSI is standard in the US.

Question 3

What is mmHg?

Accepted Answer

mmHg (millimeters of mercury) is a pressure unit based on the height of a mercury column. It's commonly used in medicine for blood pressure measurements and in meteorology. 760 mmHg = 1 atm.

Question 4

Are Torr and mmHg the same?

Accepted Answer

Practically yes. 1 Torr = 1 mmHg to within 2 parts per million. The Torr was historically defined more precisely, but for almost all practical purposes they are interchangeable.

Question 5

What is a Pascal?

Accepted Answer

The Pascal (Pa) is the SI unit of pressure, defined as one newton per square meter. It's very small — standard atmospheric pressure is 101,325 Pa. Kilopascal (kPa) and megapascal (MPa) are more commonly used.

Question 6

What is normal tire pressure?

Accepted Answer

Typical car tire pressure is 30-35 PSI (2.07-2.41 bar or 207-241 kPa). Check your vehicle's door jamb sticker for the recommended pressure. Under-inflated tires reduce fuel efficiency and safety.

Question 7

What pressure units are used for blood pressure?

Accepted Answer

Blood pressure is measured in mmHg. Normal blood pressure is around 120/80 mmHg (systolic/diastolic). High blood pressure (hypertension) is generally defined as 130/80 mmHg or above.

Question 8

How do I convert PSI to bar?

Accepted Answer

Divide PSI by 14.504 to get bar. For example, 30 PSI ÷ 14.504 ≈ 2.07 bar. Alternatively, multiply PSI by 0.06895 for the same result.

Reference	Bar	PSI	ATM	kPa	mmHg
Vacuum (near)	0	0	0	0	0
Tire pressure	2.1	30.5	2.1	210	1,575
Atmosphere	1.013	14.7	1	101.3	760
Bike tire	6.9	100	6.8	690	5,175
SCUBA tank	200	2,900	197	20,000	150,000
Mariana Trench	1,086	15,750	1,072	108,600	815,000

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