Percentage Concentration to Molarity Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Jan 25, 2023

If you have a substance and you want to quickly convert the percentage of concentration to molarity, our tool does so in three simple steps.

Don't worry if you don't know the molar mass of a given solution – we've provided you with a list of the most popular ones. Remember that our calculator works both ways – you don't need to enter your values from top to bottom.

In the text below, we will discuss solutions, density, and how to convert percentage concentration into molarity, manually 👏

How to use the convert percentage concentration to molarity calculator?

Calculating molarity with our calculator will probably take you less time than it did to read the title of this section 😉

Follow the steps below to quickly obtain your result:

  1. Do you know the molar mass of your substance?

    If you don't, try to find it on our list of the most popular substances used in chemistry. Please choose the custom option and enter the known value if you know it.

    Molar mass is the mass of 1 mole of a substance, given in g/mol. 1 mol consists of exactly 6.02214076 × 10²³ particles.

💡 6.02214076 × 10²³... What does this number mean? Check the Avogadro's number calculator to find out!

❗ Molar mass is not to be mistaken with molecular weight – the mass of a single molecule of a substance, given in daltons (e.g., a single HO particle is 18 u). You may need the periodic table to calculate molar mass.

Even though both of these variables are similar in value, they describe different things.

  1. Enter the density of your solution.

    Remember to double check the conditions of the reaction, concentration and the dilution of your solution!

  2. Enter the percentage concentration of your solution or the molarity of your solution.

    The molarity, A.K.A. the molar concentration, describes the number of moles in a given volume of solution. We usually use units like 1 mol/L (moles per liter) = 1 mol/dm³ (moles per cubic decimetre) = 1 M (molar).

  3. Your results have been calculated! 🎉

You can also check if your chemical reactions are taking place in standard temperature and pressure 🌡️

How do I convert molarity to percentage concentration?

Here's the equation we use to convert the percentage concentration to molarity:

Molarity = (Percentage concentration × Density ) / (Molar mass × 100)

The units required for this calculation are:

  • Molarity -> mol/dm³ = M = mol/L;
  • Percentage concentration -> %;
  • Density -> g/L = g/dm³; and
  • Molar mass -> g/mol.

Be careful – the density of a solution is usually given in g/mL or g/cm³ or kg/m³! Our calculator will help you will all the conversions, so don't stress.

Check our other useful tools for molar mass & solutions:


Molar mass (g/mol)



Acetic acid








Hydrochloric acid


Hydrogen peroxide


Nitric acid


Phosphoric acid


Potassium hydroxide


Sodium chloride


Sodium hydroxide


Sulfuric acid



How do I find the molar mass of a substance?

The molar mass value is usually equal to the molecular weight of the substance. Remember to change the unit to g/mol.

How do I calculate the molecular weight of water?

To determine the molecular weight of H₂O:

  1. Take a look at the periodic table of elements – find the atomic mass (given in u) of oxygen (O) and hydrogen (H).
  2. To create water, we'll need two particles of hydrogen (2 × 1u) and one particle of oxygen (1 × 16 u).
  3. Add it all together: the molecular weight of water is equal to 18 u.

How do I find percentage concentration given molarity?

If you know molarity as well as the molar mass and density, you can determine the percentage concentration via the following formula: Percentage concentration = (Molarity × Molar mass × 100)/ Density. Remember, the unit now is the percent %.

Łucja Zaborowska, MD, PhD candidate
Your molar mass:
Density of solution
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