Science, Tech, Math › Science Converting Atmospheres to Bars Share Flipboard Email Print The pressure units atmospheres and bars may be used to calculate underwater pressure as well as atmospheric pressure. Jeff Rotman / 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 August 27, 2018 This example problem demonstrates how to convert the pressure units bar (bar) to atmospheres (atm). Atmosphere originally was a unit related to the air pressure at sea level. It was later defined as 1.01325 x 105 pascals. A bar is a pressure unit defined as 100 kilopascals. This makes one atmosphere nearly equal to one bar, specifically: 1 atm = 1.01325 bar. 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 bars? Solution: 1 atm = 1.01325 barSet up the conversion so the desired unit will be canceled out. In this case, we want the bar to be the remaining unit.pressure in bar = (pressure in atm) x (1.01325 bar/1 atm)pressure in bar = (99.136 x 1.01325) barpressure in bar = 100.45 bar Answer: The water pressure at a depth of 1 km is 100.45 bar.