Advanced Molar Ratio Calculator

What this calculator does: It converts a known amount into moles, applies the stoichiometric ratio, and reports theoretical and yield-adjusted target amounts.

Calculator Inputs

Reaction or Process Name

Known Species

Target Species

Known Amount

Known Amount Unit

Known Species Molar Mass (g/mol)

Target Species Molar Mass (g/mol)

Known Species Coefficient

Target Species Coefficient

Percent Yield (%)

Gas Molar Volume (L/mol)

Decimal Places

Formula Used

1) Convert known input to moles

Moles = given moles
Moles = mass ÷ molar mass
Moles = molecules ÷ Avogadro constant
Moles = gas volume ÷ molar volume

2) Apply the stoichiometric ratio

Target moles = Known moles × (Target coefficient ÷ Known coefficient)

3) Adjust for reaction yield

Actual target moles = Theoretical target moles × (Percent yield ÷ 100)

4) Convert target moles to other forms

Mass = moles × molar mass
Molecules = moles × 6.02214076 × 10²³
Gas volume = moles × molar volume

How to Use This Calculator

Enter the reaction name or paste a balanced equation.
Type the known species and the target species labels.
Choose the known input unit.
Enter the known amount.
Fill in the balanced-equation coefficients.
Provide molar masses when mass conversion is needed.
Set percent yield for actual production estimates.
Click Calculate Molar Ratio.
Review the result cards and chart.
Use the CSV or PDF buttons to export the output.

Example Data Table

Reaction	Known Species	Known Amount	Known Coefficient	Target Species	Target Coefficient	Theoretical Target Moles
2H₂ + O₂ → 2H₂O	H₂	4.00 mol	2	H₂O	2	4.00 mol
N₂ + 3H₂ → 2NH₃	H₂	9.00 mol	3	NH₃	2	6.00 mol
CaCO₃ → CaO + CO₂	CaCO₃	50.0 g	1	CO₂	1	0.4995 mol
4Fe + 3O₂ → 2Fe₂O₃	O₂	11.2 L	3	Fe₂O₃	2	0.3333 mol

Frequently Asked Questions

1) What is a molar ratio?

A molar ratio compares substances using coefficients from a balanced chemical equation. It shows how many moles of one substance react with or produce another substance.

2) Why must the equation be balanced first?

Balanced equations preserve atoms. Their coefficients create the correct stoichiometric relationship. Without balancing, every mole conversion becomes chemically incorrect.

3) Can I start with grams instead of moles?

Yes. Enter grams as the known unit and provide the known substance molar mass. The calculator converts grams into moles before applying the ratio.

4) What does percent yield change?

Percent yield adjusts theoretical output to a practical result. It estimates the amount actually produced in the lab or plant after real losses.

5) Can I use gas volume as input?

Yes. Choose gas volume at STP and enter the molar volume used by your convention. The default value supports standard stoichiometric gas conversions.

6) What if I do not know the target molar mass?

The calculator still returns target moles, molecules, and gas volume. Only gram-based target outputs need the target substance molar mass.

7) Does this calculator find the limiting reagent?

No. This version assumes one known reference substance. For limiting reagent work, compare all reactants separately and use the smallest theoretical product result.

8) When is molar ratio useful?

It is useful in stoichiometry homework, reagent planning, yield estimation, reactor calculations, gas-law conversions, and mass-to-mass chemistry problems.