Convert standard atmosphere to bar.

Convert standard atmosphere (atm) to bar (bar). This is a fixed-ratio conversion — multiply the input by the factor below.

Formula

bar = atm × 1.01325

Reference values

Things to watch for

• psi can be gauge (psig, above atmospheric) or absolute (psia). At sea level, psia = psig + 14.7. Specify which.
• 1 atm = 14.696 psi = 1.01325 bar = 101.325 kPa = 760 mmHg. These are all defined exactly.
• For tire pressure use psi or bar; for weather mbar/hPa; for vacuum work torr or Pa; for industrial fluid power MPa.

What is a standard atmosphere?

One standard atmosphere equals exactly 101,325 pascals — the average atmospheric pressure at sea level. Diving (depth = atm + 1 per 10 m of water), chemistry, and atmospheric reference.

What is a bar?

One bar equals exactly 100,000 pascals — close to but not exactly equal to one standard atmosphere. European industrial pressure, tire pressure in some regions, and meteorology.

How to picture a atm

It's often easier to understand a unit when paired with familiar examples. 1 atm is standard atmospheric pressure at sea level; 2 atm is the pressure at 10 meters underwater; and 100 atm is about the pressure 1 km deep in the ocean.

How to convert standard atmosphere to bar

To convert a value from standard atmosphere (atm) to bar (bar), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in atm.
2. Apply the formula bar = atm × 1.01325.
3. The result is your value in bar.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert atm to bar?

Apply the formula atm → bar shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, atm or bar?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then bar is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then bar is the larger unit.

When would I use atm versus bar?

Both units measure pressure, so the choice depends on context. Standard atmosphere is typically used for tires, weather, hydraulics, and material strength; bar similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this atm to bar conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

Related conversions

See also