A standard atmosphere is exactly 101,325 pascals.
Atmospheres to inHgs Converter — atm to inHg
Convert Atmosphere (atm) to inHg (inHg) using the exact conversion factor (1 atmosphere = 29.9212524 inhg). See the formula, worked examples, conversion table, and common uses.
Atmospheres to inHgs converter
Converter
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mercury columns, water columns, and engineering pressure units.
Context values
Some unit families need one extra value for a physically accurate result.
Inches of mercury.
Result = input x 101325 / 3386.389.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Atmospheres to inHgs
Atmosphere and inHg both show up on pressure gauges — psi is standard on US tire and tool specifications, while bar is the everyday pressure unit across most of the rest of the world. Atmosphere is most often used for chemistry (standard conditions are often defined at 1 atm).
Formula
inhgs = atmospheres × 29.9212524019
This factor comes from each unit's defined relationship to the category's base unit: 1 atmosphere equals 101325 base units, and 1 inhg equals 3386.389 base units, so dividing one by the other gives the direct atmosphere-to-inhg factor of 29.9212524019.
Simple example
1 atm × 29.9212524 = 29.9212524 inHg
1 atmosphere = 29.9212524 inhgs.
Real-world example
35 atm × 29.9212524 = 1,047.243834 inHg
35 atmospheres = 1,047.243834 inhgs.
Conversion table
| Atmosphere (atm) | inHg (inHg) |
|---|---|
| 1 atm | 29.9212524 inHg |
| 5 atm | 149.606262 inHg |
| 10 atm | 299.212524 inHg |
| 25 atm | 748.03131 inHg |
| 50 atm | 1,496.06262 inHg |
| 100 atm | 2,992.12524 inHg |
Reverse conversion: inHg to Atmosphere
29.9212524 inHg × 0.03342106094 = 0.9999999999 atm
29.9212524 inhgs = 0.9999999999 atmospheres.
atmospheres = inhgs × 0.0334210609425
For a page dedicated to this direction, see inHg to Atmosphere.
Understanding the Atmosphere
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
Where it's used: Widely used internationally in chemistry, meteorology, and diving/aviation contexts alongside the pascal and bar
Uses of the Atmosphere today
- Chemistry (standard conditions are often defined at 1 atm)
- Diving and aviation pressure references
- General reference for everyday atmospheric pressure
Understanding the inHg (inHg)
Inches of mercury.
Atmosphere — sources
- BIPM SI Brochure — Standard atmosphere listed among non-SI units with a fixed exact value in pascals.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many inhgs are in 1 atmosphere?
1 atmosphere equals 29.9212524 inhgs, using the exact defined conversion factor rather than an estimate.
How do I convert atmosphere to inhg?
Multiply the atmosphere value by 29.9212524. The converter above does this instantly to whatever precision you set.
How do I convert inhg back to atmosphere?
Use the reverse factor: 1 inhg equals 0.0334210609 atmospheres. You can also use the swap control in the converter above to flip the direction instantly.
What is a atmosphere?
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
What is a inhg?
inHg (inHg) is a unit of pressure.
Is the atmosphere to inhg conversion exact?
Yes. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the atmosphere still used today?
Widely used internationally in chemistry, meteorology, and diving/aviation contexts alongside the pascal and bar