Atom Economy Calculator
Measure how efficiently a reaction converts reactant mass into the desired product — the percentage atom economy, a key green-chemistry metric.
How it works
% atom economy = ( molar mass of desired product / total molar mass of all reactants ) × 100
Atom economy asks what fraction of the atoms in the reactants actually end up in the product you want, rather than in by-products or waste. Unlike percent yield, which measures how well a reaction runs, atom economy is fixed by the balanced equation itself and reflects the inherent efficiency of the chemistry. A high atom economy is a core goal of green chemistry because it means less material is discarded per unit of product.
Worked example
In an addition reaction that builds glycerol (product molar mass 92.09 g/mol) from reactants totalling 138.12 g/mol per mole of product: atom economy = (92.09 / 138.12) × 100 = 66.7 %. The remaining 33.3 % of reactant mass leaves as by-products.
Sources: Atom economy — Wikipedia
Frequently asked questions
How is atom economy different from percent yield?
Percent yield measures how much product you actually get versus the theoretical maximum, and depends on the conditions. Atom economy is set purely by the reaction equation — the best possible use of atoms even at 100 % yield.
Which reactions have the highest atom economy?
Addition and rearrangement reactions, where all reactant atoms are incorporated, can reach 100 %. Substitution and especially elimination reactions lose atoms as by-products and score lower.
What counts in the total reactant mass?
Every reactant that appears in the balanced equation, each multiplied by its stoichiometric coefficient. Catalysts and solvents are not consumed and are excluded.
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