Convert Atmospheres to Inches of mercury
1 standard atmosphere is 29.921252 inHg. One standard atmosphere is exactly 29.9212524019 inches of mercury.
One standard atmosphere is 29.921252 inches of mercury. To convert atmospheres to inches of mercury, multiply by 29.921252; to go the other way, divide by 29.921252 or multiply by 0.033421061. The factor is exact rather than rounded: it follows from NIST Special Publication 811.
Factor checked against the defining standard · How we check
- Atmospheres × 29.921252
value * 29.921252401929.921 inHg
1 standard atmosphere in every pressure unit
| Unit | Value | Exact factor |
|---|---|---|
| pounds per square inch | 14.69594878 psi | × 14.6959487755 |
| bars | 1.01325 bar | × 1.01325 |
| pascals | 101,325 Pa | × 101,325 |
| kilopascals | 101.325 kPa | × 101.325 |
| megapascals | 0.101325 MPa | × 0.101325 |
| atmospheres (as entered) | 1 atm | — |
| torr | 760 Torr | × 760 |
| inches of mercury | 29.9212524 inHg | × 29.9212524019 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert atmospheres to inches of mercury?
- 1.Take the measurement in atmospheres.
- 2.Multiply by 29.921252 — that is how many inches of mercury fit in one standard atmosphere.
- 3.To go back the other way, divide by 29.921252, or multiply by 0.033421061.
Worked example: 25 atmospheres to inches of mercury
- Formula
- atm × 29.921252 = inHg
- Arithmetic
- 25 × 29.921252 = 748.03131 inHg
- Answer
- 25 atm = 748.03131 inHg
The factor is rounded for display; the figure above is computed from the full value.
Atmospheres to inches of mercury conversion table
| Atmospheres | Inches of mercury |
|---|---|
| 1 atm | 29.921252 inHg |
| 2 atm | 59.842505 inHg |
| 3 atm | 89.763757 inHg |
| 4 atm | 119.68501 inHg |
| 5 atm | 149.606262 inHg |
| 6 atm | 179.527514 inHg |
| 7 atm | 209.448767 inHg |
| 8 atm | 239.370019 inHg |
| 9 atm | 269.291272 inHg |
| 10 atm | 299.212524 inHg |
| 12 atm | 359.055029 inHg |
| 15 atm | 448.818786 inHg |
| 20 atm | 598.425048 inHg |
| 25 atm | 748.03131 inHg |
| 50 atm | 1,496.06262 inHg |
| 100 atm | 2,992.12524 inHg |
| 200 atm | 5,984.25048 inHg |
| 300 atm | 8,976.375721 inHg |
| 500 atm | 14,960.626201 inHg |
| 1000 atm | 29,921.252402 inHg |
| 2000 atm | 59,842.504804 inHg |
| 5000 atm | 149,606.26201 inHg |
| 10000 atm | 299,212.524019 inHg |
What is a standard atmosphere?
Exactly 101,325 pascals by definition, not by measurement — it was fixed as a reference, and the real pressure outside your window is never precisely it.
What is an inch of mercury?
The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals. US aviation altimeters and barometers read in it.
How many inches of mercury are in a standard atmosphere?
One standard atmosphere is 29.921252 inches of mercury. Going the other way, one inch of mercury is 0.033421061 atmospheres. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every pressure unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Pounds per square inch | psi | 6894.7573 pascal |
| Bars | bar | 100000 pascal |
| Pascals | Pa | the base unit |
| Kilopascals | kPa | 1000 pascal |
| Megapascals | MPa | 1000000 pascal |
| Atmospheres | atm | 101325 pascal |
| Torr | Torr | 133.32237 pascal |
| Inches of mercury | inHg | 3386.389 pascal |
Questions people actually ask
- How many inches of mercury are in a standard atmosphere?
- 29.921252. The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals. US aviation altimeters and barometers read in it.
- How do I convert inches of mercury back to atmospheres?
- Divide by 29.921252, or multiply by 0.033421061 — they are the same operation.
Other pressure conversions
Inches of mercury to atmospheres — the same conversion the other way.