Stoichiometry Calculator
Balance any equation, then read the mole ratio of any two species as raw, simplest, and decimal, and find the limiting reactant, theoretical yield, and percent yield.
Theoretical yield
Enter a reaction
Balanced coefficients drive the mole-ratio table.
| Species | Side | Coeff. | g/mol | Available mol | Consumed or produced mol | Mass g | Remaining g |
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Mole ratio of any two species
Balance an equation in the calculator above, then choose any two species to read their mole ratio as the raw balanced coefficients, the simplest whole numbers, and the decimal.
We show the balanced-coefficient ratio first because it is the factor the balancer applies, then the simplest whole-number form and the decimal, so both teaching conventions are covered.
Numerator. The first species goes on top.
Denominator. Swap the selects to invert the ratio.
| Form | Ratio |
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Balance an equation above, then choose two species to read their mole ratio.
extent = reactant moles divided by coefficient; target moles = extent times target coefficient
How?
How this is calculated
The equation is balanced with the exact rational balancer, then each supplied reactant amount is converted to moles with the bundled atomic-mass table. The limiting extent is the smallest supplied reactant moles divided by its coefficient. Target moles and mass come from that extent and the target coefficient.
Formula: extent = reactant moles divided by coefficient; target moles = extent times target coefficient
What is a mole ratio?
Where it comes from
The coefficients of a balanced equation already count moles, so the ratio of two coefficients is the ratio of their moles. For 4 NH3 + 3 O2 = 2 N2 + 6 H2O, four moles of NH3 produce two moles of N2, so the NH3-to-N2 mole ratio is 4:2.
Reading it off any equation
The finder above balances the equation with exact rational arithmetic, then reads the two coefficients directly, so you can pull the ratio between any two species in your own reaction.
Why balancing comes first
The ratio is defined by the balanced coefficients, so an unbalanced equation gives the wrong ratio. The finder balances before it reads, so every ratio comes from a mass-conserving reaction.
Raw, simplest, and decimal
The raw 4:2 is the factor the balanced equation applies. The simplest whole-number form 2:1 states the same relationship in lowest terms. The decimal 2 is the same number written as a single figure. All three describe one relationship.
Mole ratio, molar ratio, mole-to-mole ratio, and stoichiometric factor name the same quantity: the ratio of two coefficients in a balanced equation.
Reaction mole ratio versus empirical simplest molar ratio
A reaction mole ratio compares coefficients across an equation. The simplest molar ratio of an empirical formula compares the moles of each element inside one compound, found by dividing each element's moles by the smallest, which the empirical and molecular formula tool handles.
How do you find the mole ratio from a balanced equation?
Balance the equation, then take the coefficient of the first species over the coefficient of the second in the order you want them. For 4 NH3 + 3 O2 = 2 N2 + 6 H2O, the mole ratio of NH3 to N2 is 4:2, which reduces to 2:1. The finder above does this for any two species.
Is the mole ratio the same as the coefficient ratio?
Yes. The mole ratio between two species is the ratio of their coefficients in the balanced equation, because the coefficients count moles. So 2 H2 : 1 O2 means two moles of hydrogen react with one mole of oxygen.
What is the difference between a mole ratio and a molar ratio?
They are two names for one quantity. Mole ratio, molar ratio, mole-to-mole ratio, and stoichiometric factor all mean the ratio of coefficients between two species in a balanced equation.
Do you have to balance the equation before finding the mole ratio?
Yes. The mole ratio is defined by the balanced coefficients, so an unbalanced equation gives the wrong ratio. The finder balances with exact rational arithmetic before reading the coefficients.
Should the mole ratio be reduced to simplest terms?
Both forms are correct. The raw coefficient ratio is the factor the balanced equation applies, and the simplest whole-number ratio states the same relationship in lowest terms. ChemTeam notes that a 3:3 ratio gives the same result as 1:1 in any calculation. The finder shows the raw ratio, the reduced ratio, and the decimal so your answer matches whichever form your course expects.
How do you turn a mole ratio into a theoretical or percent yield?
Convert the known amount to moles, multiply by the mole ratio to get moles of product, then multiply by the product molar mass for grams. The calculator at the top of this page runs that whole path, including the limiting reactant, theoretical yield, and percent yield, and it shows the mole ratio it applied on the result.
How is a reaction mole ratio different from the simplest molar ratio in an empirical formula?
A reaction mole ratio compares coefficients of two species across a balanced equation. An empirical-formula simplest molar ratio compares the moles of each element within one compound, found by dividing each element's moles by the smallest. The empirical and molecular formula tool covers the second case.
Sources
- OpenStax Chemistry 2e, Reaction Stoichiometry. OpenStax. Retrieved .
- OpenStax Chemistry 2e, Formula Mass and the Mole Concept. OpenStax. Retrieved .
- LibreTexts Introductory Chemistry (CK-12) 12.2: Mole Ratios. LibreTexts. Retrieved .
- ChemTeam: Stoichiometry, Mole-Mole Examples. ChemTeam. Retrieved .
- ChemTeam: Molar Ratio. ChemTeam. Retrieved .
- NIST Atomic Weights and Isotopic Compositions. NIST. Retrieved .
Method last reviewed