Atmospheres to Inches Of Mercury
Convert atmospheres to inches of mercury instantly — one atmosphere is 29.9213 inches of mercury.
| Atmospheres | Inches Of Mercury |
|---|---|
| 1 atm | 29.921252 inHg |
| 2 atm | 59.842505 inHg |
| 3 atm | 89.763757 inHg |
| 5 atm | 149.606262 inHg |
| 10 atm | 299.212524 inHg |
| 25 atm | 748.03131 inHg |
| 50 atm | 1496.06262 inHg |
| 100 atm | 2992.12524 inHg |
How to use
- Enter a value in the Atmospheres field.
- The Inches Of Mercury figure appears immediately — no button to press.
- Typing in the Inches Of Mercury field converts back to Atmospheres the same way.
- Use the reference table for the values that come up most often.
Atmospheres to Inches Of Mercury formula
The factor from atmospheres to inches of mercury is 29.9212524.
inHg = atm × 29.9212524
Why this factor: the atmosphere and the inch of mercury are both defined against the pascal, so dividing one definition by the other gives 29.9212524 directly. Both definitions are set out in full below.
To go the other way, divide by 29.9212524 — or use the Inches Of Mercury to Atmospheres converter, which is the same calculation reversed.
Worked example
Start with 100 atm. Multiply by 29.9212524 to get 2992.12524 inHg.
100 atm × 29.9212524 = 2992.12524 inHg
The converter above does this for any value you type, in either direction.
What is an atmosphere?
A standard atmosphere is a fixed reference pressure, originally average sea-level air pressure.
Definition: Defined as exactly 101,325 pascals — an exact convention, not a measurement.
Where it is used: Chemistry reference conditions, diving pressure, and high-pressure physics.
What is an inch of mercury?
An inch of mercury is the pressure of a one-inch mercury column, used for US barometric pressure.
Definition: About 3,386.389 pascals.
Where it is used: US weather barometric pressure, aircraft altimeter settings, and engine vacuum readings.
Atmospheres vs Inches Of Mercury
The atmosphere is a specialized unit while the inch of mercury is a US customary unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many inches of mercury are in an atmosphere?
One atmosphere equals 29.9212524 inches of mercury.
What is the formula to convert atmospheres to inches of mercury?
Multiply the number of atmospheres by 29.9212524. To reverse it, divide by 29.9212524 instead.
How do I convert inches of mercury back to atmospheres?
Divide by 29.9212524, which is the same as multiplying by 0.0334210609.
How many inches of mercury are in 10 atmospheres?
10 atm works out to 299.212524 inHg.
How is the atmosphere defined?
Defined as exactly 101,325 pascals — an exact convention, not a measurement.