Convert Pound per Square Inch to Millimeter of Mercury (psi → mmHg)
PSI (pounds per square inch) is the standard for American tire pressures, hydraulics, and gas-cylinder specifications.
Pound per Square Inch to Millimeter of Mercury Conversion Table
10 common values| Pound per Square Inch | Millimeter of Mercury |
|---|---|
| 1 psi | 51.714925 mmHg |
| 5 psi | 258.57463 mmHg |
| 10 psi | 517.14925 mmHg |
| 25 psi | 1,292.8731 mmHg |
| 50 psi | 2,585.7463 mmHg |
| 100 psi | 5,171.4925 mmHg |
| 200 psi | 10,342.985 mmHg |
| 500 psi | 25,857.463 mmHg |
| 1,000 psi | 51,714.925 mmHg |
| 5,000 psi | 258,574.63 mmHg |
How to Convert Pound per Square Inch to Millimeter of Mercury Manually
Step by StepConverting psi to millimeters of mercury is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in psiStart with the number of psi (psi) you want to convert.
- 2Multiply by 51.714925The conversion factor from psi to mmHg is 51.714925. Multiply your value by this number.
- 3Read the result in millimeters of mercuryThe result is your value in millimeters of mercury (mmHg).
Formula
Multiply the value in psi by 51.714925. For the reverse direction, multiply by 0.019337.
mmHg = psi × 51.714925psi = mmHg × 0.019337Tips
Use these in everyday conversions- 1 psi ≈ 6.9 kPa = 0.069 bar.
- 14.7 psi = 1 atm = 1.01 bar.
- Most US pressure gauges show psi.
Common Mistakes
Avoid these- Setting a European tyre at 35 bar instead of 35 psi — disaster.
- Confusing psi (gauge) with psia (absolute).
- Using psi in scientific papers — prefer Pa or MPa.
About Pound per Square Inch and Millimeter of Mercury
What is the Pound per Square Inch?
Pounds per square inch (psi) equals approximately 6,895 pascals and is the standard pressure unit in American tire pressures, hydraulics, and gas-cylinder specifications. American car tires are typically inflated to 30–35 psi, household water systems run at 40–60 psi, and scuba tanks are filled to 3,000 psi (about 200 bar). The psi is essential in American engineering for stress calculations, hydraulic systems, and pneumatic equipment. Two variants exist: 'psig' (gauge, measured above atmospheric) and 'psia' (absolute, including atmosphere) — gauge is the default unless specified. The psi relates to the pascal (1 psi ≈ 6,895 Pa), the kilopascal (1 psi ≈ 6.895 kPa), the bar (14.504 psi = 1 bar), the atmosphere (14.696 psi = 1 atm), and the inch of mercury (1 inHg ≈ 0.491 psi). Outside the US, kPa or bar dominate.
- US tyre pressures
- US plumbing and water system specs
- US compressed-air tool ratings
US tyre: 32–35 psi. Water supply: 40–60 psi. SCUBA tank: 3000 psi. Car AC system: 30–200 psi.
What is the Millimeter of Mercury?
The millimeter of mercury equals approximately 133.322 pascals and is the universal medical unit for blood pressure measurements worldwide. Normal blood pressure is around 120/80 mmHg (systolic/diastolic). The unit's origin is the manometer: a column of mercury rises 1 mm for every 133 Pa of pressure difference. Mercury barometers historically measured atmospheric pressure (760 mmHg = 1 atm at sea level). Beyond medicine, mmHg appears in vacuum-system specifications, certain laboratory contexts, and altimeter settings (in inHg in the US, in mmHg or hPa elsewhere). The mmHg relates to the torr (1 mmHg ≈ 1.0000003 torr — essentially identical), the pascal (1 mmHg ≈ 133.3 Pa), the atmosphere (760 mmHg = 1 atm), and inches of mercury (1 inHg = 25.4 mmHg). The unit's persistence in medicine reflects historical inertia and the precision of mercury manometers.
- Blood pressure measurement globally
- Vacuum-system specifications
- Historical scientific texts
Normal blood pressure: 120/80 mmHg. Atmospheric: 760 mmHg. Good vacuum: <1 mmHg.