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Atom Economy Calculator

Chemistry
Balanced or unbalanced. Use -> or → as the arrow. States, hydrates, parentheses and charges are accepted.

Example reactions

Balanced as: C2H4O2 + C2H6O → C4H8O2 + H2O

Tick by-products that are sold or reused. Off by default.
Atom economy
83.02%

88.106 g useful of 106.121 g reactants

Mass balance check: 106.121 g in = 106.121 g out

Waste fraction
16.98%
Stoichiometric carbon efficiency
100.00%
This is a good atom economy. The small by-product is the unavoidable cost of the reaction type, so the best savings now come from yield and solvent use.

Mass flow

Useful (atom economy)

Waste

Species table

SpeciesνM (g/mol)ν·M (g)Role
C2H4O2160.05260.052Reactant
C2H6O146.06946.069Reactant
C4H8O2188.10688.106Desired product
H2O118.01518.015Waste

Where the atoms go

Reactant mass of each element, split into what ends up in the useful product and what is wasted. Sorted by waste.

O

31.998 g used · 15.999 g wasted

H

8.064 g used · 2.016 g wasted

C

48.044 g used · 0.000 g wasted

Into product

Wasted

About This Tool

Atom Economy Calculator – How Much of Your Reactants Ends Up in the Product?

This atom economy calculator balances your chemical equation, lets you pick the product you want and reports the share of reactant mass that ends up in it. If you also enter the masses you actually used, it adds the real-world green chemistry metrics: reaction mass efficiency (RME), E-factor, process mass intensity (PMI) and carbon efficiency.

Atom economy: Trost's definition

Barry Trost introduced atom economy in 1991 as a way to judge a reaction by what it builds rather than by its yield alone. For a balanced equation the formula is:

AE = (νp · Mp) / Σ(νi · Mi) × 100

Here ν is the balanced coefficient and M the molar mass. Because mass is conserved, the reactant total equals the product total, and the tool shows both as a check. Scaling every coefficient by the same factor does not change the answer.

Atom economy versus yield

Yield tells you how well an experiment performed against its theoretical maximum. Atom economy tells you how high that maximum can ever be. A substitution such as making 1-bromobutane from butanol, sodium bromide and sulfuric acid can give a 100% yield and still have an atom economy below 50%, because sodium hydrogen sulfate and water are built into the equation as by-products. Addition, cycloaddition and rearrangement reactions reach 100% because every atom is kept.

From atom economy to RME

In practice you rarely use exact stoichiometric amounts. The experimental section breaks the final efficiency into three factors:

RME = ε × AE / SF

ε is the fractional yield, AE the atom economy and SF the stoichiometric factor, which is the mass of reactants you weighed divided by the mass the limiting reagent actually needed. SF is always at least 1, and it grows when you use an excess of a reagent. The waterfall chart shows how much each factor removes, in percentage points.

E-factor, PMI and carbon efficiency

Roger Sheldon's E-factor is the mass of waste per mass of product. The simple E-factor counts only unconverted reactant mass, while the complete E-factor adds solvents, water, catalysts and work-up chemicals. PMI, used by the ACS Green Chemistry Institute Pharmaceutical Roundtable, is the total input mass per mass of product, so PMI = complete E-factor + 1. Carbon efficiency is the fraction of carbon atoms in the reactants that ends up in the product.

Industry benchmarks

Sheldon's sector table (Green Chem. 2007, 9, 1273) gives order-of-magnitude E-factors: oil refining below 0.1, bulk chemicals about 1 to 5, fine chemicals 5 to 50 and pharmaceuticals 25 to 100 or more. The gauge places your simple and complete E-factors on this scale. The simple and complete split follows Roschangar and co-workers (Green Chem. 2015).

A classic case study

The Boots and BHC syntheses of ibuprofen are the standard teaching example. The older six-step Boots route is commonly quoted at an overall atom economy of about 40%, while the three-step BHC route reaches about 77%, and recovers its acetic acid by-product to go higher still. The gap is entirely a matter of route design, not yield.

Limits of the metrics
Atom economy ignores solvents, energy and hazard, so a high value does not make a process green by itself. Use it alongside E-factor and PMI, and enter every solvent and work-up material in the auxiliary rows.

How to use the calculator

  1. Type the equation, balanced or not, or load one of the examples.
  2. Choose the desired product. Tick co-products only if they are genuinely sold or reused.
  3. Read the atom economy, the mass-flow strip and the element chart that shows where the waste atoms sit.
  4. Switch on "I ran this reaction", enter masses, purity and auxiliaries, and read RME, E-factors and PMI.

Frequently Asked Questions

Is the Atom Economy Calculator free?

Yes, Atom Economy Calculator is totally free :)

Can I use the Atom Economy Calculator offline?

Yes, you can install the webapp as PWA.

Is it safe to use Atom Economy Calculator?

Yes, any data related to Atom Economy Calculator only stored in your browser (if storage required). You can simply clear browser cache to clear all the stored data. We do not store any data on server.

How does the atom economy calculator work?

It balances your equation, sums each species' molar mass from its atomic composition, and divides the mass of the desired product (coefficient × molar mass) by the total mass of all reactants. The result is the percentage of reactant mass that ends up in the product when the reaction goes perfectly.

What is the difference between atom economy and percent yield?

Atom economy is fixed by the balanced equation and says how much of the reactant mass could ever end up in the product. Percent yield compares what you actually isolated with the theoretical maximum. A reaction can have a 100% yield and still have a poor atom economy if it makes a lot of by-product.

What is reaction mass efficiency and how does it relate to atom economy?

Reaction mass efficiency (RME) is the isolated product mass divided by the total reactant mass you used. It equals yield × atom economy ÷ stoichiometric factor, so it combines the theoretical limit (AE), how well the reaction performed (yield) and how much excess reagent you used (SF).

What is the difference between the simple and complete E-factor?

The simple E-factor counts only the reactants that did not end up in the product, while the complete E-factor also adds auxiliary materials such as solvents, water, catalysts and work-up chemicals. Process mass intensity (PMI) is the complete E-factor plus one.

What does co-product credit do?

Ticking a co-product treats it as useful output, for example when a by-product is sold or reused. The result is then labelled atom economy with co-product credit so it is not mistaken for the textbook value, which counts only the desired product.

Can I use charged species or half-reactions?

Atom economy works from atomic composition, so charged species are accepted, but it is defined for full chemical equations and half-reactions with electrons give misleading values. The experimental section is switched off for charged species because the yield service cannot reliably handle charges in formulas.