Science, Tech, Math › Science The Chemical Composition of Air Share Flipboard Email Print Tetra Images / Getty Images Science Chemistry Chemical Laws Basics 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 July 07, 2019 Nearly all of the Earth's atmosphere is made up of only five gases: nitrogen, oxygen, water vapor, argon, and carbon dioxide. Several other compounds are also present. Although this CRC table does not list water vapor, air can contain as much as 5% water vapor, more commonly ranging from 1-3%. The 1-5% range places water vapor as the third most common gas (which alters the other percentages accordingly). Below is the composition of air in percent by volume, at sea level at 15 C and 101325 Pa. Nitrogen -- N2 -- 78.084%Oxygen -- O2 -- 20.9476%Argon -- Ar -- 0.934%Carbon Dioxide -- CO2 -- 0.0314%Neon -- Ne -- 0.001818%Methane -- CH4 -- 0.0002%Helium -- He -- 0.000524%Krypton -- Kr -- 0.000114%Hydrogen -- H2 -- 0.00005%Xenon -- Xe -- 0.0000087%Ozone -- O3 -- 0.000007%Nitrogen Dioxide -- NO2 -- 0.000002%Iodine -- I2 -- 0.000001%Carbon Monoxide -- CO -- traceAmmonia -- NH3 -- trace Reference CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.