Science, Tech, Math › Science Converting Atmospheres to Pascals (atm to Pa) Share Flipboard Email Print Reinhard Dirscherl/Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated May 07, 2019 Atmospheres and Pascals are two important units of pressure. This example problem demonstrates how to convert the pressure units atmospheres (atm) to pascals (Pa). Pascal is an SI pressure unit that refers to newtons per square meter. Atmosphere originally was a unit related to the air pressure at sea level. It was later defined as 1.01325 x 105 Pa. atm to Pa Problem The pressure under the ocean increases roughly 0.1 atm per meter. At 1 km, the water pressure is 99.136 atmospheres. What is this pressure in pascals? Solution:Start with the conversion factor between the two units: 1 atm = 1.01325 x 105 PaSet up the conversion so the desired unit will be canceled out. In this case, we want Pa to be the remaining unit. pressure in Pa = (pressure in atm) x (1.01325 x 105 Pa/1 atm)pressure in Pa = (99.136 x 1.01325 x 105) Papressure in Pa = 1.0045 x 107 Pa Answer:The water pressure at a depth of 1 km is 1.0045 x 107 Pa. Pa to atm Conversion Example It's easy to work the conversion going the other way — from Pascal to atmospheres. The average atmospheric pressure on Mars is about 600 Pa. Convert this to atmospheres. Use the same conversion factor, but check to make certain Pascals cancel out so you get an answer in atmospheres. pressure in atm = (pressure on Pa) x (1 atm/1.01325 x 105 Pa)pressure in atm = 600 / 1.01325 x 105 atm (the Pa unit cancels out)pressure on Mars = 0.00592 atm or 5.92 x 10-2 atm In addition to learning the conversion, it's worth noting the low atmospheric pressure means humans couldn't breathe on Mars even if the air had the same chemical composition as air on Earth. The low pressure of the Martian atmosphere also means water and carbon dioxide readily undergo sublimation from the solid to the gas phase.