Molecular Formula Calculator

Calculate the molecular formula of a compound using its empirical formula, empirical formula mass, and actual molar mass. The calculator finds the whole-number multiplier and gives the final molecular formula instantly.

Instant Result Chemistry Tool Step-by-Step

Calculate Molecular Formula

Enter the empirical formula, empirical formula mass, and actual molar mass.

Example: For empirical formula CH2O, empirical formula mass 30.03 g/mol and molecular molar mass 180.16 g/mol, the multiplier is approximately 6.

Empirical Formula Example: CH2O, NO2, C2H5

Empirical Formula Mass (g/mol) Enter the molar mass of one empirical formula unit.

Molecular Molar Mass (g/mol) Enter the known molar mass of the compound.

Multiplier (n) n = Molecular Molar Mass ÷ Empirical Formula Mass

Main Formula:
n = Molecular Molar Mass ÷ Empirical Formula Mass
Molecular Formula = Empirical Formula × n

Molecular Formula

Empirical Mass -

Molecular Molar Mass -

Multiplier (n) -

Chemistry Guide

What Is a Molecular Formula?

A molecular formula shows the actual number of atoms of each element present in one molecule of a compound. An empirical formula instead shows the simplest whole-number ratio between the elements.

For example, CH₂O can be an empirical formula, while C₆H₁₂O₆ is six times that empirical formula.

Main Equation

Molecular Formula Calculator Formula

The molecular formula is determined by comparing the compound's molar mass with its empirical formula mass. Their ratio provides the multiplier used to convert the empirical formula into the molecular formula.

n = Molecular Molar Mass ÷ Empirical Formula Mass Molecular Formula = (Empirical Formula) × n

How It Works

How to Calculate Molecular Formula

Enter Empirical Formula

Enter the simplest formula of the compound, such as CH2O.

Enter Mass Values

Enter the empirical formula mass and the known molecular molar mass.

Get Molecular Formula

The calculator determines n and multiplies each empirical formula subscript by it.

Worked Example

Molecular Formula Example

Suppose the empirical formula is CH₂O, its empirical formula mass is approximately 30.03 g/mol, and the compound's molar mass is approximately 180.16 g/mol.

n = 180.16 ÷ 30.03 ≈ 6 CH₂O × 6 = C₆H₁₂O₆

Quick Comparison

Empirical Formula vs Molecular Formula

Feature	Empirical Formula	Molecular Formula
Meaning	Simplest whole-number ratio	Actual number of atoms
Example	CH₂O	C₆H₁₂O₆
Relationship	Base ratio	Whole-number multiple
Can They Be the Same?	Yes. They are the same when the multiplier n equals 1.

Important Information

Understanding the Molecular Formula Multiplier

The ratio between molecular molar mass and empirical formula mass should normally be close to a positive whole number. Small differences can occur because atomic masses or experimental measurements may have been rounded.

Quick Tip: If your calculated multiplier is approximately 1.00, 2.00, 3.00, 4.00, or another whole number, use that whole number to multiply every subscript in the empirical formula.

Frequently Asked Questions

Molecular Formula Calculator FAQs

What is a molecular formula?

A molecular formula shows the actual number of atoms of each element in one molecule of a compound.

How do you calculate molecular formula?

Divide the compound's molecular molar mass by its empirical formula mass. Round the resulting ratio to the appropriate whole number and multiply every empirical formula subscript by that value.

What does n mean in a molecular formula calculation?

The value n is the whole-number multiplier connecting the empirical formula to the molecular formula.

Can molecular and empirical formulas be identical?

Yes. When n equals 1, the empirical formula is already the molecular formula.

How do I calculate empirical formula mass?

Add the atomic masses of every atom represented in the empirical formula while accounting for each element's subscript.

Why should the multiplier be a whole number?

A molecular formula represents whole numbers of atoms, so it must be a whole-number multiple of its empirical formula.

What if my multiplier is 5.99?

A result such as 5.99 is usually interpreted as approximately 6 when the difference comes from normal rounding or measurement precision.

What information is needed to find a molecular formula?

You need the empirical formula, empirical formula mass, and the actual molar mass of the compound.