Convert between millimeters of mercury and atmospheres for medical, scientific, and weather applications.
Millimeters of mercury and atmospheres are both pressure units tied to the mercury-barometer tradition. mmHg is common in medicine and some laboratory settings, while atmospheres remain common in chemistry and general reference-pressure discussions.
This converter handles both directions and makes the standard relationship clear: 760 mmHg equals 1 atm. It is useful when a medical or vacuum-style reading needs to be compared with a gas-law or standard-pressure value expressed in atmospheres.
Use it when you need to move between mmHg readings and atm-based reference points without manual division by 760. It also helps when you are checking whether a reading is close to standard atmospheric pressure, comparing a manometer value with a chemistry problem, or translating a textbook atmosphere reference into the mmHg scale used on older instruments and many clinical references. Keeping those units aligned is useful whenever one source is written for clinicians or instrument operators and another is written for chemistry or physics work.
mmHg is familiar in blood pressure and mercury-column history, while atmospheres are familiar in chemistry and general pressure reference points. This page bridges those contexts directly, keeps the 760 mmHg = 1 atm anchor visible, and makes it easier to compare a reading with standard atmospheric pressure without doing the division manually each time.
ATM = mmHg ÷ 760 mmHg = ATM × 760 1 atm = 760 mmHg
Result: 0.5 atm
380 mmHg divided by 760 equals 0.5 atm, which is half of standard atmospheric pressure.
The mmHg unit comes from the height of a mercury column needed to balance a pressure. That history is why it remains familiar in blood pressure measurement and other settings tied to mercury-column instruments.
Atmospheres are convenient when comparing a pressure with standard ambient conditions or using gas-law relationships. Converting from mmHg to atm is often the quickest way to turn a medical or lab-style number into a general scientific reference pressure.
A number in mmHg may represent blood pressure, chamber pressure, or barometric pressure. The unit alone does not tell you whether the value is gauge or absolute, so always check the measurement context before comparing it with an atmosphere-based calculation.
1 atmosphere equals 760 mmHg. That fixed relationship is the basis of the whole conversion.
Divide the mmHg value by 760. For example, 380 mmHg is 0.5 atm.
Multiply atmospheres by 760. For example, 1.2 atm equals 912 mmHg.
It comes from mercury-column instruments and remains the standard way to report blood pressure. Even though modern devices are digital, the unit stayed in common clinical use.
They are extremely close and often treated as interchangeable for practical work, though their formal definitions are slightly different. In most everyday lab or medical calculations, the difference is negligible unless a strict standard requires otherwise.
Standard atmospheric pressure is 760 mmHg. That is the same reference point as 1 atm.