Convert Millimeter of Mercury to Pound per Square Inch (mmHg → psi)
The millimeter of mercury is the standard medical unit for blood pressure measurements worldwide.
Millimeter of Mercury to Pound per Square Inch Conversion Table
10 common values| Millimeter of Mercury | Pound per Square Inch |
|---|---|
| 1 mmHg | 0.019337 psi |
| 5 mmHg | 0.096684 psi |
| 10 mmHg | 0.193368 psi |
| 25 mmHg | 0.483419 psi |
| 50 mmHg | 0.966839 psi |
| 100 mmHg | 1.933678 psi |
| 200 mmHg | 3.867356 psi |
| 500 mmHg | 9.668389 psi |
| 1,000 mmHg | 19.336777 psi |
| 5,000 mmHg | 96.683887 psi |
How to Convert Millimeter of Mercury to Pound per Square Inch Manually
Step by StepConverting millimeters of mercury to psi is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in millimeters of mercuryStart with the number of millimeters of mercury (mmHg) you want to convert.
- 2Multiply by 0.019337The conversion factor from mmHg to psi is 0.019337. Multiply your value by this number.
- 3Read the result in psiThe result is your value in psi (psi).
Formula
Multiply the value in millimeters of mercury by 0.019337. For the reverse direction, multiply by 51.714925.
psi = mmHg × 0.019337mmHg = psi × 51.714925Tips
Use these in everyday conversions- 1 mmHg ≈ 133.32 Pa ≈ 1 Torr.
- 760 mmHg = 1 atm.
- Blood-pressure cuffs display mmHg worldwide.
Common Mistakes
Avoid these- Confusing mmHg with mmH₂O (different unit, factor of 13.6).
- Mixing mmHg with torr in precise vacuum physics — they differ by one part per million.
- Writing blood pressure in kPa — use mmHg for medical continuity.
About Millimeter of Mercury and Pound per Square Inch
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.
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.