Convert Atmospheres to Millimeters of Mercury
Instantly convert Atmospheres (atm) to Millimeters of Mercury (mmHg) with our free online calculator.
Formula: atm to mmHg — multiply by 760.002
Reference Table
| Atmospheres (atm) | Millimeters of Mercury (mmHg) |
|---|---|
| 1 | 760.002 |
| 5 | 3800.01 |
| 10 | 7600.02 |
| 25 | 19000.1 |
| 50 | 38000.1 |
| 100 | 76000.2 |
How to Convert Atmospheres to Millimeters of Mercury
Formula
To convert Atmospheres (atm) to Millimeters of Mercury (mmHg): multiply by 760.002
Step-by-Step
- Start with your value in Atmospheres (atm).
- Multiply by 760.002 to perform the conversion.
- The result is your value expressed in Millimeters of Mercury (mmHg).
Conversion Factor
1 atm = 760.002 mmHg
Reverse Factor
1 mmHg = 0.00131579 atm
Worked Example
Convert 25 Atmospheres to Millimeters of Mercury: 25 atm = 19000.1 mmHg
About Atmosphere (atm)
A non-SI unit of pressure defined as exactly 101,325 pascals, corresponding to the standard sea-level atmospheric pressure as adopted by ISO 2533 and the BIPM SI Brochure. Atmospheres are the default reference pressure in physical chemistry (Standard Temperature and Pressure conventions: 1 atm at 273.15 K under IUPAC's 'STP' definition, though IUPAC has since moved to 1 bar STP), in commercial diving (depths are quoted in atmospheres absolute, with each 10 m of seawater adding ~1 atm), and in pressure-sensitive materials research where vapor pressure and saturation data are tabulated at 1 atm. A common pitfall: the "technical atmosphere" (at, 98,066.5 Pa = 1 kgf/cm²) used in some legacy European and Japanese engineering is NOT the same as the standard atmosphere — older pressure-vessel drawings can read 100 at and mean either depending on context. 1 atm = 1.01325 bar = 14.696 psi = 760 mmHg = 760 torr.
About Millimeters of Mercury (mmHg)
A unit of pressure historically defined as the pressure exerted by a column of mercury exactly 1 millimeter tall at the standard acceleration of gravity (9.80665 m/s²) and the standard density of mercury (13,595.1 kg/m³ at 0 °C). The mmHg's contemporary definition rounds to exactly 133.322387415 Pa (NIST SP 811). Despite being non-SI, mmHg remains the international clinical standard for blood pressure measurement ("120 over 80" mmHg) per WHO and ESH guidelines, and is the default unit for intraocular pressure in ophthalmology (normal IOP 10-21 mmHg per Glaucoma Research Foundation) and intracranial pressure monitoring in neurology. Numerically the mmHg is almost identical to the torr (1 mmHg ≈ 1.0000007 torr — the difference is whether one uses the conventional density or the experimentally measured density of mercury). Barometric atmospheric pressure was historically quoted in mmHg before kPa/hPa adoption (760 mmHg = 1 atm = 101.325 kPa).
Quick Facts
- 1 Atmosphere equals 760.002 Millimeters of Mercury
- 1 Millimeters of Mercury equals 0.00131579 Atmospheres
- Atmosphere is a unit of pressure
- Millimeters of Mercury is a unit of pressure
- This conversion is commonly used in tire inflation, weather reporting, scuba diving, and engineering
- The Millimeters of Mercury belongs to the metric system
Common Atmosphere to Millimeters of Mercury Conversions
| Atmospheres (atm) | Millimeters of Mercury (mmHg) |
|---|---|
| 0.1 | 76.0002 |
| 0.5 | 380.001 |
| 1 | 760.002 |
| 2 | 1520 |
| 5 | 3800.01 |
| 10 | 7600.02 |
| 14.696 | 11169 |
| 15 | 11400 |
| 20 | 15200 |
| 25 | 19000.1 |
| 50 | 38000.1 |
| 100 | 76000.2 |
| 150 | 114000 |
| 200 | 152000 |
| 500 | 380001 |
| 1000 | 760002 |
Understanding Atmospheres
The Atmosphere (symbol: atm) is a unit of pressure. A non-SI unit of pressure defined as exactly 101,325 pascals, corresponding to the standard sea-level atmospheric pressure as adopted by ISO 2533 and the BIPM SI Brochure. Atmospheres are the default reference pressure in physical chemistry (Standard Temperature and Pressure conventions: 1 atm at 273.15 K under IUPAC's 'STP' definition, though IUPAC has since moved to 1 bar STP), in commercial diving (depths are quoted in atmospheres absolute, with each 10 m of seawater adding ~1 atm), and in pressure-sensitive materials research where vapor pressure and saturation data are tabulated at 1 atm. A common pitfall: the "technical atmosphere" (at, 98,066.5 Pa = 1 kgf/cm²) used in some legacy European and Japanese engineering is NOT the same as the standard atmosphere — older pressure-vessel drawings can read 100 at and mean either depending on context. 1 atm = 1.01325 bar = 14.696 psi = 760 mmHg = 760 torr.
Atmospheres are commonly used in tire inflation, weather reporting, scuba diving, and engineering.
Understanding Millimeters of Mercury
The Millimeters of Mercury (symbol: mmHg) is a unit of pressure. A unit of pressure historically defined as the pressure exerted by a column of mercury exactly 1 millimeter tall at the standard acceleration of gravity (9.80665 m/s²) and the standard density of mercury (13,595.1 kg/m³ at 0 °C). The mmHg's contemporary definition rounds to exactly 133.322387415 Pa (NIST SP 811). Despite being non-SI, mmHg remains the international clinical standard for blood pressure measurement ("120 over 80" mmHg) per WHO and ESH guidelines, and is the default unit for intraocular pressure in ophthalmology (normal IOP 10-21 mmHg per Glaucoma Research Foundation) and intracranial pressure monitoring in neurology. Numerically the mmHg is almost identical to the torr (1 mmHg ≈ 1.0000007 torr — the difference is whether one uses the conventional density or the experimentally measured density of mercury). Barometric atmospheric pressure was historically quoted in mmHg before kPa/hPa adoption (760 mmHg = 1 atm = 101.325 kPa).
It belongs to the metric measurement system.
Millimeters of Mercury are commonly used in tire inflation, weather reporting, scuba diving, and engineering.
Why Convert Atmospheres to Millimeters of Mercury?
Engineers, mechanics, and scientists frequently need to convert pressure between Atmospheres and Millimeters of Mercury when working with different measurement standards. Tire pressure, blood pressure readings, weather barometric measurements, and industrial process specifications may all use different pressure units depending on the region or discipline. Reliable conversion prevents equipment misuse and ensures safety.
Frequently Asked Questions
How do I convert Atmospheres to Millimeters of Mercury?
A non-SI unit of pressure defined as exactly 101,325 pascals, corresponding to the standard sea-level atmospheric pressure as adopted by ISO 2533 and the BIPM SI Brochure. To convert Atmospheres to Millimeters of Mercury, multiply by 760.002. For example, 25 atm equals 19000.1 mmHg.
How many Millimeters of Mercury are in 1 Atmosphere?
There are 760.002 Millimeters of Mercury in 1 Atmosphere.
How many Atmospheres are in 1 Millimeters of Mercury?
There are 0.00131579 Atmospheres in 1 Millimeters of Mercury.
What is the formula for Atmosphere to Millimeters of Mercury conversion?
The formula is: multiply by 760.002. This means 1 atm = 760.002 mmHg.
Is a Atmosphere bigger than a Millimeters of Mercury?
No. One Atmosphere is smaller than one Millimeters of Mercury because 1 atm equals 760.002 mmHg, which is greater than 1.
When do you need to convert between Atmospheres and Millimeters of Mercury?
A unit of pressure historically defined as the pressure exerted by a column of mercury exactly 1 millimeter tall at the standard acceleration of gravity (9. Atmosphere and Millimeters of Mercury are both pressure units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.