atm to mbar Converter

How to convert atmospheres to millibars

Formulambar = atm × 1,013.25

Multiply the value in atmospheres by 1,013.25. To go the other way, multiply by 0.0009869232667 (or divide by 1,013.25).

A standard atmosphere is larger than a millibar: one standard atmosphere contains 1,013.25 millibars.

Worked examples

1 standard atmosphere1 atm × 1,013.25 = 1,013.25 mbar
5 atmospheres5 atm × 1,013.25 = 5,066.25 mbar
10 atmospheres10 atm × 1,013.25 = 10,132.5 mbar
20 atmospheres20 atm × 1,013.25 = 20,265 mbar
100 atmospheres100 atm × 1,013.25 = 101,325 mbar

Atmospheres to millibars conversion table

Values are calculated by the conversion engine and rounded to 8 significant figures.

Atmospheres to millibars: 0.1–10 atm
Atmospheres (atm)	Millibars (mbar)
0.1 atm	101.325 mbar
0.25 atm	253.3125 mbar
0.5 atm	506.625 mbar
1 atm	1,013.25 mbar
2 atm	2,026.5 mbar
3 atm	3,039.75 mbar
4 atm	4,053 mbar
5 atm	5,066.25 mbar
6 atm	6,079.5 mbar
7 atm	7,092.75 mbar
8 atm	8,106 mbar
9 atm	9,119.25 mbar
10 atm	10,132.5 mbar

Atmospheres to millibars: 12–1,000 atm
Atmospheres (atm)	Millibars (mbar)
12 atm	12,159 mbar
15 atm	15,198.75 mbar
20 atm	20,265 mbar
25 atm	25,331.25 mbar
30 atm	30,397.5 mbar
40 atm	40,530 mbar
50 atm	50,662.5 mbar
75 atm	75,993.75 mbar
100 atm	101,325 mbar
250 atm	253,312.5 mbar
500 atm	506,625 mbar
1,000 atm	1,013,250 mbar

About the units

Standard atmosphere (atm)

Exactly 101,325 Pa — average sea-level air pressure.

Millibar (mbar)

The millibar (mbar) is a unit of pressure in the metric system. One millibar equals 100 pascals (Pa).

Frequently asked questions

How many millibars are in one standard atmosphere?

There are 1,013.25 millibars in one standard atmosphere, and this value is exact by definition.

How do I convert atmospheres to millibars?

Multiply the number of atmospheres by 1,013.25. For example, 10 atm × 1,013.25 = 10,132.5 mbar.

How many atmospheres are in one millibar?

One millibar equals 0.0009869232667 atmospheres. That is the reverse factor, 1 ÷ 1,013.25.

What is 10 atmospheres in millibars?

10 atm = 10,132.5 mbar.

Is this atm to mbar converter accurate?

Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.