Limiting Reagent Calculator
Find which reactant runs out first and how much of the others remains, from masses, molar masses and balanced-equation coefficients.
Reactant consumed first; it caps the reaction yield
- 1
H2: mass ÷ molar mass ÷ coefficient
10 ÷ 2,016 ÷ 2 = 2,4802 - 2
O2: mass ÷ molar mass ÷ coefficient
64 ÷ 32 ÷ 1 = 2Smallest ratio — this is the limiting reagent. - 3
O2 moles (limiting reagent)
64 ÷ 32 = 2
Miten tämä laskin toimii?
For each reactant, divide its moles (mass ÷ molar mass) by its balanced coefficient. The reactant with the smallest result is the limiting reagent and is used up first. Each other reactant's excess equals its moles minus coefficient times that smallest ratio, in moles.
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How this is calculated
Enter one reactant per line as name, mass (g), molar mass (g/mol) and its stoichiometric coefficient from the balanced equation. The calculator converts each mass to moles with moles = mass / molar mass, then divides those moles by the coefficient to get a normalized ratio that represents how many "reaction units" each reactant can supply.
The reactant with the smallest ratio is the limiting reagent: it is exhausted first and therefore sets the maximum extent of the reaction. The amount of every other reactant actually required is coefficient × (smallest ratio); whatever moles remain above that requirement is the excess. The bar chart compares each reactant's ratio so the shortest bar is the bottleneck.
Assumptions: the equation must already be balanced, masses are in grams and molar masses in g/mol, and the reaction goes to completion. Coefficients and molar masses must be positive; a molar mass of zero or a missing field is rejected. Mixing units or supplying fewer than two reactants will prevent a valid result.
Usein kysytyt kysymykset
It is the reactant that is completely consumed first, limiting how much product can form. All other reactants are in excess and leftover amounts remain when the reaction stops.
Coefficients describe the molar ratio in which reactants combine. Dividing moles by the coefficient normalizes each reactant to the same reaction scale, so the smallest result is the true bottleneck regardless of differing coefficients.
For each non-limiting reactant, required moles = coefficient × smallest ratio. The excess is the reactant's available moles minus that requirement, expressed in moles.
Tunnetaan myös nimellä
TG we-Calculate Editorial Team. (2026). Limiting Reagent Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/fi/calculator/limiting-reagent-calculator
TG we-Calculate Editorial Team. "Limiting Reagent Calculator." TG we-Calculate. 2026. https://we-calculate.com/fi/calculator/limiting-reagent-calculator.
TG we-Calculate Editorial Team, "Limiting Reagent Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/fi/calculator/limiting-reagent-calculator
@misc{wecalculate_limiting_reagent_calculator, title = {Limiting Reagent Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/fi/calculator/limiting-reagent-calculator}}, year = {2026}, note = {TG we-Calculate} }
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