Convert millimeters of mercury to atmospheres
Converting millimeters of mercury to atmospheres is a common pressure task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 mmHg equals 0.00131579 atm, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert millimeters of mercury to atmospheres
To convert millimeters of mercury to atmospheres, multiply the number of millimeters of mercury by 0.00131579. For example, 10 mmHg × 0.00131579 = 0.0131579 atm.
atm = mmHg × 0.00131579
- Write down the value in millimeters of mercury you want to convert.
- Multiply it by 0.00131579 (the exact mmHg→atm factor).
- The result is your value in atmospheres. Check it below with the converter or the table.
Conversion table
Common values of millimeters of mercury and their equivalents in atmospheres:
| mmHg | atm |
|---|---|
| 1 | 0.00131579 |
| 2 | 0.00263158 |
| 3 | 0.00394737 |
| 4 | 0.00526316 |
| 5 | 0.00657895 |
| 10 | 0.0131579 |
| 20 | 0.0263158 |
| 25 | 0.0328947 |
| 50 | 0.0657895 |
| 100 | 0.131579 |
| 250 | 0.328947 |
| 500 | 0.657895 |
About these units
Millimeter of Mercury (mmHg). A millimeter of mercury is the pressure exerted by a one-millimeter column of mercury, about 133.32 pascals. Blood pressure and vacuum measurements are still quoted in mmHg.
Atmosphere (atm). One standard atmosphere is defined as exactly 101,325 pascals, the reference average pressure of Earth's atmosphere at sea level. It anchors chemistry and gas-law calculations.
Frequently asked questions
How do I convert millimeters of mercury to atmospheres?
To convert millimeters of mercury to atmospheres, multiply the number of millimeters of mercury by 0.00131579. For example, 10 mmHg × 0.00131579 = 0.0131579 atm. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many atmospheres are in 1 millimeter of mercury?
1 mmHg = 0.00131579 atm. That is the fixed relationship used by this converter and by international standards.
How many millimeters of mercury are in 1 atmosphere?
1 atm = 760 mmHg. If you are converting in the opposite direction, use our Atmosphere to Millimeter of Mercury converter for the dedicated table and FAQ.
Is the millimeters of mercury to atmospheres conversion exact?
Yes. Both units are defined by international agreement, so the factor of 0.00131579 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is millimeter of mercury used for?
A millimeter of mercury is the pressure exerted by a one-millimeter column of mercury, about 133.32 pascals. Blood pressure and vacuum measurements are still quoted in mmHg.