Atmospheric Pressure Units Converter (based on 1 atm)

How to Calculate Between Atmospheric Pressure Units

The Atmospheric Pressure Units Converter converts pressure values between standard atmosphere (atm) and equivalent units used in engineering and meteorology. The conversion formula is:

\( P_{output} = P_{input} \times \frac{F_{output}}{F_{input}} \)

Where the factors \( F \) are the equivalents of 1 atm in each unit:

atm: 1
kPa: 101.325
bar: 1.01325
psia: 14.696
mm Hg (0°C): 760
in Hg (32°F): 29.9213
m H₂O (4°C): 10.3323

Select the input and output units, enter the input value, and calculate the result.

Using the Atmospheric Pressure Units Converter

This calculator is useful for fluid mechanics, HVAC, or barometry, supporting conversions between absolute pressure units referenced to 1 atm, including column heights at specified temperatures.

Select the input unit, output unit, and input the pressure value. The calculator outputs the converted value.

Example 1: Convert 1 atm to psia.

Input Unit: atm
Output Unit: psia
Input: \( 1 \)
Calculation: \( 1 \times (14.696 / 1) = 14.696 \)
Result: \( 14.696 \, \text{psia} \)

Example 2: Convert 760 mm Hg to bar.

Input Unit: mm Hg (0°C)
Output Unit: bar
Input: \( 760 \)
Calculation: \( 760 \times (1.01325 / 760) = 1.0133 \)
Result: \( 1.0133 \, \text{bar} \)

Use this tool for quick bidirectional conversions in pressure analysis.

Common FAQ

Below are frequently asked questions about atmospheric pressure unit conversions:

Q: What is standard atmosphere (1 atm)?
A: 1 atm is defined as 101.325 kPa, the average sea-level pressure.
Q: Why specify temperatures for mm Hg and m H₂O?
A: Column heights depend on fluid density at standard temperatures: 0°C for mercury, 4°C for water.
Q: Is psia the same as psi?
A: psia is absolute pressure; psi can be gauge, but here it's absolute equivalent to atm.
Q: How accurate is this calculator?
A: It provides precise results based on standard factors, rounded to 4 decimal places.
Q: Can negative values be used?
A: No, input values must be positive; invalid inputs leave the result blank.