Convert between millimeters of mercury (mmHg) and atmospheres with bidirectional conversion and reference pressures.
This page converts millimeters of mercury to atmospheres and back. Even though the file path uses a shorter name, the actual unit here is mmHg, the mercury-column pressure unit used in medical and laboratory contexts.
The conversion is anchored by the standard relationship 760 mmHg = 1 atm. That makes the page useful when a blood-pressure, chamber-pressure, or mercury-column style reading needs to be compared with standard atmospheric pressure in atm. It also serves as a clean bridge for chemistry and vacuum calculations where atm is the more convenient textbook unit. In practice, that means you can move from a mercury-column reading to a standard-pressure reference without reworking the rest of the calculation. The same bridge is useful for barometric comparisons and gas-law exercises where standard atmosphere is the target unit.
Use it when you need a direct mmHg-atm conversion without bouncing through multiple pressure units first. The result is easy to compare with barometric pressure, chamber pressure, or blood-pressure style readings without mental scaling.
mmHg and atm belong to different pressure traditions but share the same atmospheric reference point. This page bridges those contexts directly and makes the 760 mmHg = 1 atm relationship easy to apply. It is useful whenever you need to compare a mercury-column reading against standard atmosphere, especially in chemistry or vacuum work.
ATM = mmHg ÷ 760 mmHg = ATM × 760 1 atm = 760 mmHg
Result: 2 atm
1,520 mmHg divided by 760 equals 2 atmospheres.
mmHg comes from the height of a mercury column needed to balance a pressure. That history is why the unit still appears in medicine, barometry, and some laboratory equipment even though SI units are more common elsewhere.
Atmospheres are often the cleaner unit for chemistry, gas laws, and standard-pressure comparisons. If a pressure starts in mmHg but needs to be compared with ambient conditions or textbook formulas, converting to atm is usually the quickest bridge.
The conversion itself is simple, but the meaning of the number depends on the setting. A medical blood-pressure reading in mmHg is not used the same way as an atmospheric or chamber pressure, even if the unit conversion is identical.
760 mmHg. That is the standard atmospheric reference used in chemistry, barometry, and vacuum work.
Divide mmHg by 760. For example, 380 mmHg equals 0.5 atm, which is a quick midpoint check for common pressures.
Multiply atmospheres by 760. A value of 1.25 atm therefore becomes 950 mmHg.
It remains standard in blood pressure reporting and persists in laboratory and barometric contexts because of historical mercury-column instruments. The unit is familiar to clinicians and still appears on a lot of legacy equipment.
mmHg and Torr are extremely close and are often treated as interchangeable in everyday practice. The difference is tiny enough that it rarely changes a practical result.
It means standard atmospheric pressure, which is 760 mmHg. That reference point is the baseline for many gas-law and vacuum calculations.