How many atm is 1 mmHg?

1 millimeter of mercury (mmHg) equals approximately 0.0013157895 standard atmospheres. This comes from the exact definition: 1 atm = 101,325 Pa and 1 mmHg = 133.322387415 Pa, so 1 mmHg / 101,325 Pa ≈ 0.0013157895 atm.

How do I convert mmHg to atm manually?

Divide the mmHg value by 760. For example, 380 mmHg ÷ 760 = 0.5 atm. To convert atm back to mmHg, multiply by 760. This works because 1 atm is defined as exactly 760 mmHg.

What is the difference between mmHg and atm?

Millimeter of mercury (mmHg) is a pressure unit equal to the pressure exerted by a 1 mm column of mercury at 0 °C under standard gravity (133.322 Pa). A standard atmosphere (atm) is defined as exactly 101,325 Pa. Standard atmospheric pressure at sea level is 760 mmHg = 1 atm.

Is mmHg the same as Torr?

For all practical purposes, 1 mmHg ≈ 1 Torr. Strictly, 1 Torr = 101,325/760 Pa ≈ 133.3224 Pa, while 1 mmHg = 133.3224 Pa by the mercury-density definition. The difference is less than 0.000016%, so they are interchangeable in medical and laboratory use.

What is standard atmospheric pressure in mmHg and atm?

Standard atmospheric pressure is defined as exactly 101,325 Pa, which equals 760 mmHg and 1 atm. This is the baseline reference used in chemistry, meteorology, and engineering worldwide.

When is mmHg used instead of atm?

mmHg is the standard in medicine (blood pressure, eye pressure), vacuum technology, and historical meteorology. Atmospheres are common in chemistry, diving, and general physics. This converter is useful whenever you encounter specs in one unit but need the other.

mmHg to Atmospheres Converter

Name: mmHg to Atmospheres Converter
Availability: InStock
Author: Nham Vu

Enter a pressure in mmHg and get the standard atmosphere (atm) equivalent instantly, with reverse atm-to-mmHg conversion included.

Converter

Pressure in millimeters of mercury (mmHg)

Result in atmospheres (atm)

Reverse: atmospheres to mmHg

Pressure in atm

Result in mmHg

Reference Table

mmHg Atmospheres (atm)

1 mmHg 0.0013158

10 mmHg 0.013158

76 mmHg 0.1

100 mmHg 0.13158

120 mmHg 0.15789

200 mmHg 0.26316

380 mmHg 0.5

500 mmHg 0.65789

760 mmHg 1

1520 mmHg 2

3800 mmHg 5

7600 mmHg 10

Formula: atm = mmHg ÷ 760 • mmHg = atm × 760

Summary

Enter a pressure in mmHg and get the standard atmosphere (atm) equivalent instantly, with reverse atm-to-mmHg conversion included.

How it works

Enter the pressure value in mmHg in the top input field.
The atmosphere (atm) result appears instantly with no button press needed.
Use the reverse field to convert atm back to mmHg.
Click "Copy" next to any result to copy the value to your clipboard.
Check the reference table for common mmHg-to-atm values at a glance.

Use cases

Convert blood pressure readings from mmHg to atm for chemistry or physics calculations.
Translate barometric pressure from mmHg to atm when comparing weather data across sources.
Convert vacuum pump specifications from mmHg to atm for laboratory equipment setup.
Cross-check mercury manometer readings against atm-based pressure references.
Convert altitude-based atmospheric pressure from mmHg to atm in aviation contexts.
Verify gas cylinder pressures that mix mmHg and atm across different supplier specs.
Convert ophthalmological intraocular pressure readings from mmHg to atm for research.
Translate historical barometric data recorded in mmHg into standard atmospheres.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu