Science, Tech, Math › Science Acids and Bases - Calculating pH Worked Chemistry Problems Share Flipboard Email Print pH is a measure of acidity. 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 Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated August 20, 2018 pH is a measure of the acidity or alkalinity of a chemical solution. A solution with a pH less than 7 is considered to be acidic. One with a pH greater than 7 is alkaline. A pH equal to 7 is a neutral solution. Here is a simple example of how to calculate the pH of a solution when the hydrogen ion concentration is known: Question What is the pH of a solution with [H+] = 1 x 10-6 M. Solution pH is calculated by the formula pH = - log [H+] Substitute [H+] with the concentration in the question. pH = - log (1 x 10-6)pH = -(-6)pH = 6 Answer The pH of the solution is 6.