Percentage Concentration To Molarity Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Aug 05, 2021

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. If you do know it, please choose the custom option and enter the known value.

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

❗ Molar mass is not to be mistaken with molecular weight - the mass of a single molecule of a substance, given in daltons (e.g., 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 amount 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 conditions 🌡️

How to 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

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.

  • Molar mass -> g/mol

The expression can be rearranged to find the percentage concentration:

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

Check our other useful tools for molar mass & solutions:

SubstanceMolar mass (g/mol)
Ammonia 17.03
Acetic acid 60.05
Hydrochloric acid36.46
Hydrogen peroxide34.01
Nitric acid63.01
Phosphoric acid97.99
Potassium hydroxide 56.11
Sodium chloride58.44
Sodium hydroxide40.0
Sulfuric acid 98.08

How did we create that?

We used the fact that the molar mass value is usually equal to the molecular weight of the substance.

Let's try to calculate the molecular weight of water (H₂O).

  1. Take a look at the period 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.
Łucja Zaborowska, MD, PhD candidate
Your molar mass:
Density of solution
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