Science calculators

Chemistry helpers such as molar mass with a per-element breakdown and mass percent composition.

Molecular Weight CalculatorType a chemical formula to get its molar mass in g/mol, a breakdown by element with mass percent, and quick grams-to-moles conversions.

Science guides

A round glass dish on white paper in a laboratory

Molar Mass vs. Molecular Weight vs. Formula Mass: What's the Difference?Clear definitions of molar mass, molecular weight, formula mass and atomic mass units, why their numbers match, and how to calculate each from a chemical formula.3 min read

A scientist using a pipette with test tubes in a lab

Grams to Moles and Moles to Grams: Conversions with Worked ExamplesConvert between grams, moles and number of particles using molar mass and Avogadro's number, with step-by-step examples and a stoichiometry walkthrough.2 min read

Test tubes filled with different colored liquids

Percent Composition by Mass: How to Calculate It and Why It MattersCalculate the mass percent of each element in a compound from its formula, check the result, and use percent composition in labs, nutrition labels and fertilizers.2 min read