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mmHg to atm Converter

1 mmHg = 0.00131579 atm (millimeter of mercury → standard atmosphere)

1 mmHg = 0.00131579 atm

1 millimeter of mercury equals 0.00131579 standard atmospheres. To convert millimeters of mercury to standard atmospheres, multiply the millimeter of mercury value by 0.00131579. For quick reference: 1 mmHg = 0.00131579 atm, 5 mmHg = 0.00657895 atm, 10 mmHg = 0.0131579 atm, 100 mmHg = 0.131579 atm.

When to use millimeters of mercury → standard atmospheres

Millimetres of mercury to standard atmospheres divides by about 760 (101,325 ÷ 133.322387415 = 759.9998 mmHg per atm). A 380 mmHg partial-pressure figure is 0.5 atm; a barometer at 745 mmHg reads 0.980 atm. Chemistry gas-law work and altitude physiology both use this pairing — oxygen partial pressures at elevation are classically tabulated in mmHg against atm references. The mmHg and the torr (exactly 1/760 atm) are nearly identical but not the same unit; only in high-precision vacuum work does the distinction surface.

Hyperbaric-chamber protocols sometimes record chamber pressure in millimetres of mercury from legacy manometers, then express the reading as a fraction of a standard atmosphere for patient charts. A reading of 380 mmHg is exactly 0.500 atm, half of sea-level pressure and roughly equivalent to 5,500 m altitude; 570 mmHg is 0.750 atm. Because 1 atm was historically defined as 760 mmHg, this conversion is exact rather than approximate, which is why hyperbaric medicine still tolerates mmHg readings even in an otherwise SI-standardised clinical setting.

How to convert millimeters of mercury to standard atmospheres

  1. Take your value

    Start with your value in millimeters of mercury.

  2. Multiply by 0.00131579

    Multiply the millimeter of mercury value by 0.00131579. This is the exact conversion factor from millimeters of mercury to standard atmospheres.

  3. Read the result

    The product is your value in standard atmospheres. For example, 5 mmHg × 0.00131579 = 0.00657895 atm.

Conversion formula

The exact factor from millimeters of mercury to standard atmospheres is 0.00131579.

Standard atmospheres = Millimeters of mercury × 0.00131579

Millimeters of mercury to Standard atmospheres conversion table

Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.

Conversion table from millimeters of mercury to standard atmospheres
Millimeters of mercury (mmHg)Standard atmospheres (atm)
0.001 mmHg1.3158 × 10^−6 atm
0.01 mmHg1.3158 × 10^−5 atm
0.1 mmHg0.00013158 atm
0.5 mmHg0.00065789 atm
1 mmHg0.0013158 atm
1.5 mmHg0.0019737 atm
2 mmHg0.0026316 atm
2.5 mmHg0.0032895 atm
3 mmHg0.0039474 atm
4 mmHg0.0052632 atm
5 mmHg0.0065789 atm
6 mmHg0.0078947 atm
7 mmHg0.0092105 atm
8 mmHg0.010526 atm
9 mmHg0.011842 atm
10 mmHg0.013158 atm
14 mmHg0.018421 atm
15 mmHg0.019737 atm
20 mmHg0.026316 atm
25 mmHg0.032895 atm
30 mmHg0.039474 atm
32 mmHg0.042105 atm
35 mmHg0.046053 atm
40 mmHg0.052632 atm
50 mmHg0.065789 atm
60 mmHg0.078947 atm
75 mmHg0.098684 atm
80 mmHg0.10526 atm
100 mmHg0.13158 atm
101.325 mmHg0.13332 atm
150 mmHg0.19737 atm
200 mmHg0.26316 atm
250 mmHg0.32895 atm
300 mmHg0.39474 atm
400 mmHg0.52632 atm
500 mmHg0.65789 atm
760 mmHg1 atm
1000 mmHg1.3158 atm
1013.25 mmHg1.3332 atm
2000 mmHg2.6316 atm
5000 mmHg6.5789 atm
10000 mmHg13.158 atm
14.7 mmHg0.019342 atm
50000 mmHg65.789 atm
100000 mmHg131.58 atm
101325 mmHg133.32 atm
200000 mmHg263.16 atm
500000 mmHg657.89 atm
1000000 mmHg1315.8 atm
10000000 mmHg13158 atm

Real-world reference

Normal blood pressure is around 120/80 mmHg. Atmospheric pressure at sea level is roughly 760 mmHg.

Frequently asked questions

How many standard atmospheres are in 1 millimeter of mercury?
1 millimeter of mercury equals 0.00131579 standard atmospheres.
How do I convert millimeters of mercury to standard atmospheres?
Multiply the millimeter of mercury value by 0.00131579. So x mmHg × 0.00131579 = the equivalent in atm.
What is 5 millimeters of mercury in standard atmospheres?
5 millimeters of mercury equals 0.00657895 standard atmospheres.
What is 10 millimeters of mercury in standard atmospheres?
10 millimeters of mercury equals 0.0131579 standard atmospheres.
What is 100 millimeters of mercury in standard atmospheres?
100 millimeters of mercury equals 0.131579 standard atmospheres.
How do I convert back from standard atmospheres to millimeters of mercury?
Multiply the standard atmosphere value by 760. For example, 1 atm = 760 mmHg.
Is the millimeter of mercury bigger than the standard atmosphere?
No. 1 millimeter of mercury is smaller than 1 standard atmosphere. It takes 760 millimeters of mercury to equal 1 standard atmosphere.
Are these conversion factors exact?
The factor is derived directly from the SI definitions of millimeter of mercury and standard atmosphere; the displayed value is rounded for readability, and the browser computes using IEEE 754 double-precision arithmetic.

About the millimeter of mercury and the standard atmosphere

The millimeter of mercury

The millimeter of mercury (mmHg) equals approximately 133.322 Pa — the pressure exerted by a 1 mm column of mercury under standard gravity. It is the conventional unit for blood pressure worldwide, even in countries that have otherwise gone fully metric.

The standard atmosphere

The standard atmosphere (atm) is defined as exactly 101,325 Pa. It is the conventional reference for chemistry (gas-law calculations), aviation altimetry, and historic engineering. Despite the name, it is not the actual atmospheric pressure at any single place — that varies daily.

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