Atmospheres to PSI (atm to psi) Converter

A complete pressure unit conversion tool. Enter a value in any field to instantly convert between **Atmospheres (atm)**, **PSI**, **Bar**, **Kilopascals (kPa)**, and **Torr (mmHg)**.

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The Difference: atm vs. bar vs. Pascal

The main source of confusion when converting pressure is the similarity between "atm" and "bar". They are close in value but are not the same.

  • Pascal (Pa): This is the base SI unit for pressure. It's very small (1 N/m²), so we almost always use **Kilopascals (kPa)** (1,000 Pa) or **Megapascals (MPa)** (1,000,000 Pa).
  • Bar: A simple metric unit. 1 bar = 100,000 Pa exactly. This is very close to atmospheric pressure.
  • Standard Atmosphere (atm): This is an older unit, defined as the *average* atmospheric pressure at sea level. 1 atm = 101,325 Pa exactly (or 1.01325 bar).
  • PSI (Pounds per Square Inch): The Imperial unit, common in the US, defined by force (pounds) over area (square inches).
  • Torr (mmHg): A unit based on the pressure exerted by one millimeter of mercury, commonly used in meteorology and for vacuum pressures. 1 atm = 760 Torr.

Conversion Formulas

All conversions are based on the Pascal (Pa):

1 atm = 101,325 Pa
1 PSI = 6,894.757 Pa
1 bar = 100,000 Pa
1 kPa = 1,000 Pa
1 Torr = 133.322 Pa

From this, we can find the direct formula:

PSI = atm × 14.6959...
atm = PSI × 0.068046...

Common Pressure Conversion Table

Measurement atm PSI kPa Bar
Absolute Vacuum 0 0 0 0
Standard Atmosphere 1 atm 14.696 psi 101.325 kPa 1.013 bar
Car Tire Pressure ~2.2 atm ~32 psi ~220 kPa ~2.2 bar
Home Water Pressure ~3.4 atm ~50 psi ~345 kPa ~3.4 bar

Frequently Asked Questions (FAQ)

What is the formula for atm to PSI?

The exact formula is: PSI = atm × 14.6959487755. For most calculations, multiplying by 14.696 is sufficient.

How many PSI are in 1 atm?

There are **14.696 PSI** (Pounds per Square Inch) in 1 standard atmosphere (atm).

Is 1 bar the same as 1 atm?

No. They are very close, but 1 standard atmosphere (atm) is slightly larger than 1 bar. 1 atm = 1.01325 bar.