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Molecular Formula Calculator

Molecular Formula Calculator


Molar Mass (M)


Mass of Empirical Formulas



Table of Content

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An online molecular formula calculator is exclusively programmed to calculate the molecular formula of a substance or compound based on its empirical formula. Well, we created this context for you to perform certain calculations regarding the molecular compound formula.

Let’s read on!

What Is A Molecular Formula?

In the context of chemistry:

“A particular expression displaying the exact number of the atoms that are present in a molecule of a compound or a substance is known as the molecular formula”

For example:

The following table shows formula of various compounds:

Sr. #. Name Of The Substance Molecular Substance Formula
1. Glucose  \(C_{6}H_{12}O_{6}\)
2. Sodium Chloride NaCl
3. Hydrogen Peroxide \(H_{2}O_{2}\)
4. Methane  \(CH_{4}\)
5. Water \(H_{2}O\)


Molecular Expression Steps:

Let us go through the series of various steps that are crucial to find the molecular formula:

Basic Formula Involved:

$$ \text{Molecular Formula} = n\left(\text{Empirical Formula}\right) $$


$$ n = \frac{\text{Molar Mass}}{\text{\text{Empirical Formula Mass}} $$

Note: Always keep in mind that the value of n is considered as a whole number and not any decimal number.

Here the  empirical formula to molecular formula calculator also helps you to determine the accurate substance formula by using the same relation as mentioned above.

Variables Involved:

By having a look of the formula, you will notice that two variables are used in it which are as follows:

Molar Mass:

If we divide the mass of the sample substance by its amount, we will get the molar mass of that substance.

Mass Of The Empirical Formula:

The overall mass of the simplest whole number ratio atoms in the compound is known as the mass of the empirical formula.

Inputs Conversion To Basic Units:

Here you need to calculate the basic notations of the variables involved by converting them from grams to kilograms. In case you find it difficult, tap the conversion calculator for better outcomes.

Evaluation Of The Formula:

This is the final step of all. What you need to do here is to put the values of the variables that are given. Once you put them, simplify until you get a whole number answer.

How To Calculate Molecular Formula?

Let us solve a couple of examples straight away that will clear your concept in more depth.

Example # 01:

Empirical formula of a compound of the boron and hydrogen is \(BH_{4}\). Its molar mass is 31.2 g/mol. How to calculate the molecular compound formula?


As we know that:

$$ \text{Empirical Formula Mass} = 10.811+1.008+1.008+1.008+1.008 $$
$$ \text{Empirical Formula Mass} = 14.843 g/mol $$

Now we have to find the value of n as follows:

$$ n = \frac{\text{Molar Mass}}{\text{\text{Empirical Formula Mass}} $$
$$ n = \frac{31.2}{14.843} $$

$$ n = 2 $$

$$ \text{Molecular Formula} = n\left(\text{Empirical Formula}\right) $$
$$ \text{Molecular Formula} = 2\left(BH_{4}\right) $$
$$ \text{Molecular Formula} = B_{2}H_{8} $$

Keep in mind that when you are carrying out a chemical reaction, use an empirical to molecular formula calculator for instant outputs. The reason is that manual calculations consume a lot of time and during a chemical reaction, a minor delay of seconds can disturb the whole reaction.

Example # 02:

How to determine the molecular formula of a water molecule bearing molar mass of 20g/mol?


$$ \text{Empirical Formula Mass} = 2*1.008+15.999 $$
$$ \text{Empirical Formula Mass} = 18.015 g/mol $$

Now the value of n is determined as follows:

$$ n = \frac{20}{18.015} $$
$$ n = 1 $$

Finally, we have:

$$ \text{Molecular Formula} = 1\left(H_{2}O) $$

$$ \text{Molecular Formula} = H_{2}O $$

As you see that the empirical and the molecular formula of the water molecule are the same. This is because the molecular formula of the water molecule cannot be further simplified to its corresponding empirical formula.

How Molecular Formula Calculator Works?

The free empirical formula to molecular formula calculator is considered the most reliable way to find the molecular formula and is widely used by chemists worldwide. Let us guide you how to use it!


  • First of all, write down the molar mass of the compound or the substance
  • After doing so make a selection of the molecular substance from the drop down menu
  • Then, write down the empirical formula mass of the substance
  • Also, make another selection corresponding to it from the lower drop down list
  • Tap the calculate button


The free molecular formula calculator displays:

  • Simple whole number ratio n
  • Conversions of the inputs into relative base units
  • Molecular substance formula of the compound both substance
  • Step by step calculations


What do you mean by the atomic mass unit?

The mass that is equal to the one-twelfth of the mass of the carbon atom taken as 12 is known as the atomic mass unit. The use of the amu is very important in molecular formula calculation.


$$ \text{Atomic Mass Unit} = \frac{1}{12th} \text{Mass Of The Carbon-12 $$

What do you mean by the term atomic number?

The total number of the p[rotons present in the nucleus of an atom is termed the atomic number. It is denoted by the letter Z.

For example:

As there is only one proton in the nucleus of the hydrogen atom, so its atomic number is 1.

What is meant by the mole of a substance?

In system international, the basic unit for the amount of the substance is termed as mole of the substance.

$$ \text{One Mole} = 6.02 * 10^{23} atoms $$


The molecular expression is of great importance when you wish to predict the number of the atoms in the compound.  no matter whether you are performing a lab or any ordinary experiment, this free molecular formula calculator should your best choice to make. This makes them capable of performing the chemical reactions without any hurdles and avoid making any mistake that could actually disturb the whole reaction.


From the source of wikipedia: Chemical formula, Empirical formula, Condensed formula, Law of composition, Isotopes, Trapped atoms, 

From the source of khan academy: Chemical reactions, Physical and chemical changes

From the source of lumen learning: Chemical Formulas, Structural Formulas v. Empirical Formulas, Formulas of Ionic Compounds, Polyatomic Ions