Atom Economy Calculator
Enter the molar mass and stoichiometric coefficient of the desired product, then the molar mass and coefficient of each reactant from your balanced equation. The calculator returns the atom economy, the theoretical share of reactant mass that ends up in the desired product.
Last updated: September 26, 2026
Frequently asked questions
What is atom economy?
Atom economy is the percentage of the total mass of the reactants, as shown in the balanced equation, that ends up in the desired product. The rest becomes by-products.
How is atom economy different from percent yield?
Atom economy is a theoretical property of the balanced equation. Percent yield compares the amount you actually obtained with the theoretical amount. Use the Actual Yield Calculator for percent yield.
Do the coefficients matter?
Yes. Each molar mass is multiplied by its stoichiometric coefficient from the balanced equation, so an unbalanced equation gives a meaningless result.
Can atom economy be above 100%?
No. Mass is conserved, so the desired product cannot outweigh the reactants. The calculator flags that as an input error.
Where do I get molar masses?
Use the Molecular Weight Calculator to convert a chemical formula into molar mass in g/mol.
Does this tell me how to run the reaction?
No. It is an educational stoichiometry calculator only and gives no procedures or conditions.