mmHg to atm Converter

To convert mmHg to atm, divide by 760, which is the same as multiplying by 0.00131579. 760 mmHg is 1 atm, standard atmospheric pressure.

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How It Works

A millimetre of mercury is the pressure at the bottom of a column of mercury 1 mm high: 133.322 Pa for conventional mercury (13,595.1 kg/m³ under standard gravity). The standard atmosphere is defined as 101,325 Pa, the pressure that holds up about 760 mm of mercury in a barometer at sea level.

Chemistry and physics problems, gas laws and vacuum work often give pressure in mmHg and want it in atm.

Formula

atm = mmHg × 0.00131579 (= mmHg ÷ 760)

The torr is defined as exactly 1/760 atm. The conventional mmHg is 0.14 parts per million larger, which never shows at the precision of a gauge or a homework answer.

Worked Example

A gas sample is held at 380 mmHg:

380 × 0.00131579 = 0.5 atm

mmHg to atm Table

mmHg atm kPa
1 mmHg 0.00131579 atm 0.133322 kPa
10 mmHg 0.0131579 atm 1.33322 kPa
50 mmHg 0.0657895 atm 6.66612 kPa
100 mmHg 0.131579 atm 13.3322 kPa
200 mmHg 0.263158 atm 26.6645 kPa
300 mmHg 0.394737 atm 39.9967 kPa
380 mmHg 0.5 atm 50.6625 kPa
400 mmHg 0.526316 atm 53.329 kPa
500 mmHg 0.657895 atm 66.6612 kPa
600 mmHg 0.789474 atm 79.9934 kPa
700 mmHg 0.921053 atm 93.3257 kPa
720 mmHg 0.947369 atm 95.9921 kPa
730 mmHg 0.960526 atm 97.3253 kPa
740 mmHg 0.973684 atm 98.6586 kPa
750 mmHg 0.986842 atm 99.9918 kPa
760 mmHg 1 atm 101.325 kPa
770 mmHg 1.01316 atm 102.658 kPa
800 mmHg 1.05263 atm 106.658 kPa
1,000 mmHg 1.31579 atm 133.322 kPa
1,520 mmHg 2 atm 202.65 kPa

Going the other way? Use the atm to mmHg converter. For kilopascals, use the mmHg to kPa converter.

FAQ

Common questions about converting mmHg to atmospheres.

Frequently Asked Questions

How do I convert mmHg to atm?

Divide mmHg by 760, or multiply by 0.00131579. For example, 190 mmHg × 0.00131579 = 0.25 atm.

How many atm is 1 mmHg?

1 mmHg is 0.00131579 atm, or 0.133322 kPa.

What is 750 mmHg in atm?

750 mmHg is 0.986842 atm, a typical barometric pressure a little below the standard atmosphere.

Is mmHg the same as torr?

For practical purposes, yes. The torr is defined as exactly 1/760 of a standard atmosphere, and the conventional mmHg is 0.14 parts per million larger, so 760 mmHg and 760 torr both round to 1 atm.

Why is standard atmospheric pressure 760 mmHg?

A mercury barometer at sea level holds up a column about 760 mm high, so 760 mmHg became the reference. The standard atmosphere was later fixed at 101,325 Pa, which is 760 mmHg to six figures.

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