🌿 Atom Economy Calculator
Quantify the proportion of reactant mass that becomes desired product to benchmark greener chemical syntheses.
Used for labelling results and context in supporting text (does not affect the calculation).
Reactant Data
Optional. Used to show an effective atom economy that incorporates isolated yield.
How to Use This Calculator
Collect stoichiometric data
Grab the balanced reaction. Note the molar mass and stoichiometric coefficient for the desired product and every reactant.
Enter molar masses
Fill in the molar mass (g/mol) and coefficient for the desired product, then list each reactant with its own values. Add extra reactants if needed.
Optional: include percent yield
If you want to estimate real-world efficiency, enter the isolated yield to compute an effective atom economy.
Review the results
Use the atom economy to compare alternative synthetic routes or highlight waste-minimising strategies in your report.
Formula
Atom Economy (%) = (Mdesired * nuproduct) / Sum(Mreactant * nureactant) * 100
Here nu represents the stoichiometric coefficient for each species in the balanced reaction.
Example
Aspirin synthesis: Salicylic acid (138.12 g/mol, nu = 1) + acetic anhydride (102.09 g/mol, nu = 1) → acetylsalicylic acid (180.16 g/mol, nu = 1) + acetic acid.
Atom economy = (180.16 / (138.12 + 102.09)) * 100 = 76.1%.
Full Description
Atom economy is a central green chemistry metric introduced by Barry Trost to quantify how well a reaction incorporates reactant atoms into the desired product. A high atom economy indicates that minimal atoms are diverted to by-products or waste streams, which often means lower material costs, improved process mass intensity, and fewer downstream separation steps.
This calculator lets you evaluate potential synthetic routes quantitatively. By pairing stoichiometric coefficients with molar masses, you can instantly see how alternative reagents or different protecting-group strategies impact material efficiency. The effective atom economy value folds in percent yield to approximate what happens when a reaction is transferred from the whiteboard to the lab bench.
Use the tool during reaction design, sustainability reviews, or to back up environmental impact statements in patent filings. Combined with E-factor and process mass intensity metrics, atom economy provides a holistic picture of how clean a transformation really is.
Frequently Asked Questions
What if a reactant has a fractional coefficient?
Simply enter the fractional value (for example 0.5) in the coefficient field. The calculator multiplies molar mass by the stoichiometric factor exactly as it appears in the balanced equation.
Does atom economy consider reaction yield?
Classical atom economy is independent of yield. Use the optional percent-yield field to generate an effective atom economy that reflects real laboratory outcomes.
How is atom economy different from E-factor?
Atom economy is a theoretical metric derived from stoichiometry, whereas E-factor measures actual kilograms of waste per kilogram of product. A route can have high atom economy but still produce lots of waste if yield or selectivity are poor.
Can I include catalysts or solvents?
Catalysts are usually excluded from atom economy calculations because they are regenerated. Solvents are also omitted. Focus on reactants that are consumed to form products.
Does the calculator support multi-step syntheses?
Atom economy is defined for individual reactions. Evaluate each step separately, or compute an overall value by combining balanced equations and molar masses for the net transformation.