Enter the equation
Type a balanced chemical equation using coefficients, formulas, plus signs, and an arrow.
Chemical reaction calculator
Stoichiometry Calculator
Convert between reactant and product quantities using a balanced chemical equation, molar masses, mole ratios, limiting reagents, and percent yield.
Equation balance check
Grams and moles
Limiting reagent mode
Calculation setup
Enter a balanced equation
Use coefficients, chemical formulas, plus signs, and an arrow. The calculator validates atom balance before using the mole ratio.
Use 100% for theoretical yield or enter an expected experimental yield.
Core relationship
target mol = known mol ×
(target coefficient ÷ known coefficient)
Mass values are converted to moles before the mole ratio is applied.
Calculated result
Reaction breakdown
Your result will appear here
Enter a balanced equation and known quantity to view mole ratios, molar masses, theoretical yield, and calculation steps.
Simple calculation process
How the stoichiometry calculator works
The calculator turns a balanced equation into mole ratios, then applies unit conversions and molar masses.
Validate atom balance
The tool counts each element on both sides before allowing a stoichiometric calculation.
Apply the mole ratio
Equation coefficients create the ratio between the known and target substances.
Review the result
See moles, mass, molar mass, theoretical yield, practical yield, and calculation steps.
What is a stoichiometry calculator?
A stoichiometry calculator determines the quantitative relationship between substances in a chemical reaction. It uses the coefficients of a balanced equation to convert a known amount of one substance into the expected amount of another.
The key step is converting the known quantity into moles. Once the number of moles is known, the calculator applies the coefficient ratio and converts the target moles into the requested unit.
Stoichiometric mole ratio
Target moles = Known moles × (Target coefficient ÷ Known coefficient)
For the equation 2H₂ + O₂ → 2H₂O, two moles of hydrogen react with one mole of oxygen to form two moles of water.
Mass-to-mass calculations
For a grams-to-grams problem, the calculator follows three stages:
- Convert the known mass to moles using its molar mass.
- Apply the balanced-equation mole ratio.
- Convert target moles to target mass.
Limiting reagent
When two reactant quantities are supplied, the reactant that produces the smaller reaction extent is the limiting reagent. It determines the maximum theoretical amount of product.
Helpful answers
Frequently asked questions
Learn more about balanced equations, mole ratios, molar mass, limiting reagents, and percent yield.
What is stoichiometry?
Stoichiometry is the calculation of reactant and product quantities using the coefficients in a balanced chemical equation.
Does the equation need to be balanced first?
Yes. Mole ratios come from the coefficients of a balanced equation. This calculator checks whether the equation is balanced before completing the calculation.
Can I calculate from grams to grams?
Yes. The calculator converts the known mass to moles, applies the mole ratio, and converts the target moles back to mass.
Which equation format should I use?
Use formulas separated by plus signs and an arrow, such as 2H2 + O2 -> 2H2O. Parentheses in formulas such as Ca(OH)2 are supported.
What is percent yield?
Percent yield compares an actual experimental yield with the theoretical yield. Enter a value below 100 percent to estimate an expected practical amount.
Can this calculator identify a limiting reagent?
Yes. In Limiting Reagent mode, enter available amounts for two reactants. The calculator compares their reaction extents and identifies the limiting reactant.
Are atomic masses exact?
The calculator uses commonly accepted standard atomic weights. Small differences may occur when a course or laboratory uses rounded atomic masses.