Atom Economy Calculator — Green Chemistry Efficiency
Atom economy measures how efficiently a reaction uses its reactant atoms. Enter the molar mass of your desired product and the total molar mass of all products (including by-products) to get the atom economy percentage — a key green chemistry metric.
g/mol
g/mol
Percentage of atoms in reactants that end up in the desired product
- 1
Fraction: desired ÷ total products
100 ÷ 180 = 0.55556Ratio of atoms that end up in the desired product versus all products. - 2
Atom economy (%)
0.55556 × 100 = 55.56
How does this calculator work?
Atom economy (%) = (molar mass of desired product ÷ total molar mass of all products) × 100. A score of 100% means no atoms are wasted as by-products. Enter your product masses to benchmark the green efficiency of a reaction without needing actual yield data.
Formula
How this is calculated
Atom economy, introduced by Barry Trost in 1991, quantifies how "atom-efficient" a reaction is. A 100% atom economy means every atom from the reactants ends up in the desired product — nothing is wasted. Lower values indicate more by-products and waste, which adds cost, environmental burden, and disposal challenges.
To calculate it, sum the molar masses of all products formed by the balanced equation (not the reactants), then divide the molar mass of the desired product by that total. The result, multiplied by 100, gives the atom economy percentage. For example, addition reactions (where two molecules join) typically have 100% atom economy, while substitution reactions often produce salt or other by-products and score lower.
Atom economy is a theoretical metric — it does not account for actual yield, reagent excess, solvent use, or energy consumption. Use it alongside percentage yield and the E-factor for a fuller picture of a reaction's environmental efficiency. Values are based on the stoichiometric balanced equation only.
Frequently asked questions
Above 80% is generally considered good in green chemistry. Addition and rearrangement reactions can reach 100%, while many elimination and substitution reactions are much lower. There is no universal cut-off — context and application matter.
No. Atom economy is purely theoretical — it uses stoichiometric molar masses from the balanced equation, regardless of how much product is actually isolated. Combine it with percentage yield to get a realistic picture of efficiency.
Atom economy is a theoretical ratio from stoichiometry. The E-factor (Environmental Factor) is empirical — it is the actual mass of waste generated per kilogram of product, including solvents, reagents, and unreacted starting materials.
Also known as
TG we-Calculate Editorial Team. (2026). Atom Economy Calculator — Green Chemistry Efficiency [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/atom-economy-calculator
TG we-Calculate Editorial Team. "Atom Economy Calculator — Green Chemistry Efficiency." TG we-Calculate. 2026. https://we-calculate.com/calculator/atom-economy-calculator.
TG we-Calculate Editorial Team, "Atom Economy Calculator — Green Chemistry Efficiency," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/atom-economy-calculator
@misc{wecalculate_atom_economy_calculator, title = {Atom Economy Calculator — Green Chemistry Efficiency}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/atom-economy-calculator}}, year = {2026}, note = {TG we-Calculate} }
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