---
title: "Standard atmospheres to Millibars — atm to mbar converter"
description: "1 standard atmosphere = 1,013.25 millibars. Conversion table, the exact formula, and a calculator for any value."
url: https://atoneplace.net/convert/atmospheres-to-millibars/
site: "At One Place"
---

# Standard atmospheres to millibars

**1 standard atmosphere in millibars: 1 atm = 1,013.25 mbar**

mbar = atm × 1,013.25

To convert standard atmospheres to millibars, multiply by 1,013.25. The table below gives the values people look up most often, and the converter works for any number.

## Standard atmospheres to millibars table

*Common standard atmosphere values converted to millibars.*

| Standard atmospheres | Millibars |
| --- | --- |
| 1 atm | 1,013.25 |
| 2 atm | 2,026.5 |
| 3 atm | 3,039.75 |
| 4 atm | 4,053 |
| 5 atm | 5,066.25 |
| 10 atm | 10,132.5 |
| 15 atm | 15,198.75 |
| 20 atm | 20,265 |
| 25 atm | 25,331.25 |
| 30 atm | 30,397.5 |
| 40 atm | 40,530 |
| 50 atm | 50,662.5 |
| 75 atm | 75,993.75 |
| 100 atm | 101,325 |
| 250 atm | 253,312.5 |
| 500 atm | 506,625 |
| 1,000 atm | 1,013,250 |

## How the conversion works

The relationship is mbar = atm × 1,013.25. Both units measure pressure, so the conversion is a fixed factor that never changes.

## Common questions

### How many millibars are in one standard atmosphere?

One standard atmosphere equals 1,013.25 millibars. mbar = atm × 1,013.25.

### How do you convert standard atmospheres to millibars?

Use mbar = atm × 1,013.25. So 10 atm is 10,132.5 mbar.

### How many standard atmospheres are in one millibar?

One millibar equals 0.0009869 standard atmospheres, which is the reverse of the conversion above.

## Related pages

- [Millibars to Standard atmospheres](https://atoneplace.net/convert/millibars-to-atmospheres/)
- [Standard atmospheres to Pascals](https://atoneplace.net/convert/atmospheres-to-pascals/)
- [Standard atmospheres to Kilopascals](https://atoneplace.net/convert/atmospheres-to-kilopascals/)
- [Standard atmospheres to Bars](https://atoneplace.net/convert/atmospheres-to-bar/)
- [Standard atmospheres to Pounds per square inch](https://atoneplace.net/convert/atmospheres-to-psi/)
- [Standard atmospheres to Torrs](https://atoneplace.net/convert/atmospheres-to-torr/)

## Sources

- Guide for the Use of the International System of Units (SP 811) — NIST (https://www.nist.gov/pml/special-publication-811) [Public domain (US Government)]
- The International System of Units (SI Brochure) — Bureau International des Poids et Mesures (https://www.bipm.org/en/publications/si-brochure)
- Calculated on this page — At One Place (/about/)