atm to mmHg Converter
To convert atm to mmHg, multiply by 760. 1 atm is 760 mmHg, and 0.5 atm is 380 mmHg. The same standard atmosphere is 101.325 kPa, 1.01325 bar and 14.6959 psi.
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How It Works
The standard atmosphere (atm) is defined as 101,325 Pa. A millimetre of mercury (mmHg) is the pressure under a 1 mm column of conventional mercury, 133.322 Pa, so one atmosphere holds up 760 mm of mercury.
Gas law problems, partial pressures, vacuum specifications and older laboratory data mix the two units.
Formula
mmHg = atm × 760
The torr is defined as exactly 1/760 atm, so atm to torr is exactly 760. The conventional mmHg gives the same 760 to six significant figures.
Worked Example
Dry air is 20.95% oxygen, so at 1 atm the oxygen partial pressure is 0.2095 atm:
0.2095 × 760 = 159.22 mmHg
atm to mmHg Table
| atm | mmHg | kPa | psi |
|---|---|---|---|
| 0.1 atm | 76 mmHg | 10.1325 kPa | 1.46959 psi |
| 0.25 atm | 190 mmHg | 25.3313 kPa | 3.67399 psi |
| 0.5 atm | 380 mmHg | 50.6625 kPa | 7.34797 psi |
| 0.75 atm | 570 mmHg | 75.9938 kPa | 11.022 psi |
| 0.9 atm | 684 mmHg | 91.1925 kPa | 13.2264 psi |
| 1 atm | 760 mmHg | 101.325 kPa | 14.6959 psi |
| 1.5 atm | 1,140 mmHg | 151.988 kPa | 22.0439 psi |
| 2 atm | 1,520 mmHg | 202.65 kPa | 29.3919 psi |
| 2.5 atm | 1,900 mmHg | 253.313 kPa | 36.7399 psi |
| 3 atm | 2,280 mmHg | 303.975 kPa | 44.0878 psi |
| 5 atm | 3,800 mmHg | 506.625 kPa | 73.4797 psi |
| 10 atm | 7,600 mmHg | 1,013.25 kPa | 146.959 psi |
Going the other way? Use the mmHg to atm converter. For kilopascals, use the kPa to mmHg converter.
FAQ
Common questions about converting atmospheres to mmHg.
Frequently Asked Questions
How do I convert atm to mmHg?
Multiply atm by 760. For example, 1.5 atm × 760 = 1,140 mmHg.
How many mmHg is 1 atm?
1 atm is 760 mmHg. In other units it is 101.325 kPa, 29.9213 inHg and 14.6959 psi.
What is 0.5 atm in mmHg?
0.5 atm is 380 mmHg, about the air pressure at 5,500 m above sea level.
Is 1 atm exactly 760 mmHg?
It is exactly 760 torr, because the torr is defined as 1/760 atm. With the conventional mmHg it is 759.999892 mmHg, which rounds to 760 at any precision a gauge or a textbook uses.
What is the difference between atm and bar?
1 atm is 1.01325 bar, so the atmosphere is 1.3% larger. The atmosphere is the reference pressure at sea level; the bar is a round metric unit of 100,000 Pa.
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