Millimeters of mercury (mmHg) to Atmospheres (atm) Conversion
Millimeters of mercury
The millimetre of mercury (mmHg) is a unit of pressure equal to the pressure exerted by a 1 mm column of mercury at 0 °C and standard gravity — approximately 133.322 Pa. It is the universal clinical standard for measuring blood pressure: normal adult blood pressure is approximately 120/80 mmHg (systolic/diastolic). The mmHg is also used in ophthalmology (intraocular pressure, normal ≈ 10–21 mmHg) and respiratory physiology.
Atmospheres
The standard atmosphere (atm) is a unit of pressure defined as exactly 101,325 Pa, representing the approximate mean atmospheric pressure at sea level. It remains in use in chemistry for expressing gas pressures in thermodynamic tables and standard conditions (STP: 0 °C and 1 atm). One atmosphere supports a mercury column of exactly 760 mm — the basis of the mercury barometer invented by Torricelli in 1643. In deep-sea diving, pressure is expressed in atmospheres absolute (ATA).
| Millimeters of mercury (mmHg) | Atmospheres (atm) |
|---|---|
| 0.1 mmHg | 0.000132 atm |
| 1 mmHg | 0.00132 atm |
| 2 mmHg | 0.00263 atm |
| 3 mmHg | 0.00395 atm |
| 5 mmHg | 0.00658 atm |
| 10 mmHg | 0.0132 atm |
| 20 mmHg | 0.0263 atm |
| 30 mmHg | 0.0395 atm |
| 50 mmHg | 0.0658 atm |
| 100 mmHg | 0.1316 atm |
| 1000 mmHg | 1.3158 atm |
Frequently Asked Questions (FAQ)
How many atmospheres are in 1 millimeters of mercury?
1 millimeters of mercury (mmHg) is exactly 0.001316 atmospheres (atm).
How do I convert millimeters of mercury to atmospheres?
Multiply the value in millimeters of mercury by 0.001316 to get the result in atmospheres. Or use the converter above — type any number and see the result instantly.