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To convert from millimeter of mercury (mmHg) to pound per square inch (psi), use the following formula:
pound per square inch (psi)
= 0.133322 × 0.00014503768078 × 1000× millimeter of mercury (mmHg)
= 0.01933671367695116× millimeter of mercury (mmHg)
With 0.00014503768078 is the ratio between the base units kilopound per square inch (ksi) and kilopascal (kPa).
Let's convert 5 millimeter of mercury (mmHg) to pound per square inch (psi).
Using the formula:
5 × 0.01933671367695116 = 0.0966835683847558
Therefore, 5 millimeter of mercury (mmHg) is equal to 0.0966835683847558 pound per square inch (psi).
How many millimeters of mercury are in one pound per square inch? One pound per square inch (psi) contains 51.715095786517900835 millimeters of mercury (mmHg) — the inverse of the factor above. Multiplying by 0.01933671367695116 takes you from millimeters of mercury to pounds per square inch; multiplying by 51.715095786517900835 brings you back.
Put in words: one millimeter of mercury equals 0.01933671367695116 pounds per square inch, so the millimeter of mercury is the smaller unit of this pair. Converting between them never changes the amount of pressure being measured — only the size of the unit you count it in.
A millimeter of mercury (mmHg) is a manometric unit of pressure.
It was historically defined as the pressure generated by a column of mercury exactly one millimeter high.
Today, it is most famous as the unit used in medicine for measuring blood pressure. It is also commonly used in meteorology, aviation, and physics to measure atmospheric pressure or vacuum pressure.
The mmHg unit originates from the invention of the barometer by Evangelista Torricelli in 1643.
Torricelli's device measured atmospheric pressure by seeing how high it could support a column of mercury in a tube.
Standard atmospheric pressure was found to support a column approximately 760 mm high, which established 760 mmHg as a standard reference point.
The most well-known application of mmHg is in medicine.
Blood Pressure: Readings are given as two numbers: systolic pressure (when the heart beats) over diastolic pressure (when the heart rests), such as 120/80 mmHg. This is a critical vital sign for human health.
Meteorology: Used for reporting barometric (atmospheric) pressure, which helps in weather forecasting.
Physics & Engineering: Used for measuring vacuum pressures and other low-pressure systems where precision is needed.
While mmHg is common, other pressure units are standard in different fields. Here are the most common conversions:
A pound per square inch (PSI) is a unit of pressure commonly used in the imperial system (which is standard in the United States).
It measures the amount of force applied over a single square inch of area.
PSI is a critical measurement for safety and performance in many common items, including:
Vehicle Tires: Proper tire pressure (PSI) ensures optimal handling, fuel efficiency, and tire life. You can find the recommended level on a sticker inside the driver's door.
Home Water Pressure: Affects everything from shower performance to how well appliances like dishwashers and washing machines function.
Sports Equipment: Items like footballs, basketballs, and soccer balls require a specific PSI to perform correctly and safely.
Tools: Air compressors, pressure washers, and paint sprayers all have specific PSI ratings for safe and effective operation.
While PSI is standard in the imperial system, scientific and international contexts use metric (SI) units like the Pascal (Pa) and the bar.
PSI to Pascal (Pa): The official SI unit for pressure.
1 PSI ≈ 6,894.76 Pascals (or 6.895 kilopascals, kPa).
PSI to Bar: A common unit in automotive and weather contexts. 1 bar is roughly equal to atmospheric pressure at sea level.
1 PSI ≈ 0.0689 bar.
The term "PSI" can be specified further to give more context:
PSIG (Pound-force per square inch gauge): Measures pressure relative to the surrounding atmospheric pressure. This is the most common measurement, used by a standard tire gauge.
PSIA (Pound-force per square inch absolute): Measures pressure relative to a perfect vacuum (absolute zero pressure).
The formula is: PSIA = PSIG + local atmospheric pressure.
PSID (Pound-force per square inch differential): Measures the difference in pressure between two separate points in a system, such as across a filter or valve.
Here are some quick reference conversions from millimeter of mercury (mmHg) to pound per square inch (psi):
| millimeters of mercury | pounds per square inch |
|---|---|
| 0.000001 mmHg | 1.933671367695116× 10-8 psi |
| 0.001 mmHg | 0.00001933671367695116 psi |
| 0.1 mmHg | 0.001933671367695116 psi |
| 1 mmHg | 0.01933671367695116 psi |
| 2 mmHg | 0.03867342735390232 psi |
| 3 mmHg | 0.05801014103085348 psi |
| 4 mmHg | 0.07734685470780464 psi |
| 5 mmHg | 0.0966835683847558 psi |
| 6 mmHg | 0.11602028206170696 psi |
| 7 mmHg | 0.13535699573865812 psi |
| 8 mmHg | 0.15469370941560928 psi |
| 9 mmHg | 0.17403042309256044 psi |
| 10 mmHg | 0.1933671367695116 psi |
| 20 mmHg | 0.3867342735390232 psi |
| 30 mmHg | 0.5801014103085348 psi |
| 40 mmHg | 0.7734685470780464 psi |
| 50 mmHg | 0.966835683847558 psi |
| 100 mmHg | 1.933671367695116 psi |
| 1000 mmHg | 19.33671367695116 psi |
| 10000 mmHg | 193.3671367695116 psi |
For all Pressure converters, choose units using the From/To dropdowns above.