# What is one atmosphere of pressure?

One atm. is the same (per definition) as 101325 pa. This approximately the same as ${10}^{5}$ pa which is 1 bar.
The standard atmosphere is defined as 101325 pa. As you can see, this is pretty close to ${10}^{5}$ pa which is equal to 1 bar.
Keep in mind that pressure is defined as the force exerted on a certain area. Therefore the SI unit of pressure $p a$ is the same as $N \cdot {m}^{- 2}$.