# Molarity Calculator

Created by Gabriela Diaz
Last updated: Jul 10, 2022

With the molarity calculator, you can determine the molar concentration of a solution from its mass concentration. You can also use this tool to calculate the needed mass of a solute to obtain a given volume of a solution of particular molarity.

• What is molarity?;
• How to calculate molarity with the molarity formula;
• Molarity units; and
• Molality vs molarity — What's the difference between them?

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## What is molarity?

Molarity, also known as molar concentration, is one of the most used methods for describing the concentration of a solution. This term expresses the number of moles of a substance dissolved per liter of solution.

Then, to answer the question of how to calculate molarity? We just need to know the substance's number of moles and the solution's total volume. This is summarized in the molarity formula:

$\small \text{Molarity} = \cfrac{\text{Number of moles}}{\text{Volume of solution}}$

The molar concentration unit is the molar. It's denoted by a capital M and corresponds to the number of moles per liter of solution (mol/L) or moles per cubic decimeter (mol/dm3).

The SI unit for molar concentration is the moles per cubic meter (mol/m3), however, because most chemical literature uses mol/dm3, molar (M) is more commonly used. In any case, you may always apply the following conversion:

Molarity

Molar equivalent

1 mol/L

1 M

1 mol/mL

1000 M

1 mol/dm3

1 M

1 mol/m3

1000 M

1 mmol/L

0.001 M

1 mmol/mL

1 M

1 mmol/m3

0.000001 M

Molarity is used to express concentrations in our solution dilution calculator

🙋 Please note that molarity refers to the total volume of the solution, not the solvent's volume.

## Molality vs molarity

Molarity can sometimes be confused with the term molality. While both terms are used to describe concentration in moles, molarity refers to the quantity of a substance per unit volume of solution, whereas molality defines a concentration in terms of the amount of solute per unit mass of the solvent. More specifically, molality is defined as the number of moles of solute per kilogram of solvent.

## How to use the molarity calculator

With this molarity calculator you can convert from mass concentration to molar concentration. You may also use this tool to determine the required mass of a substance to achieve a specified molarity.

Let's see how to use this tool for converting from mass to molar concentration:

1. First, you'll need to have at hand the molar mass of the substance and proceed to enter this value in the Molar mass field of the calculator.

2. Next, input the Concentration of the substance. This is the mass concentration. In the case of pure substances, it's equivalent to its density.

3. With these two inputs, the calculator will display the molar concentration of the substance in the Molarity field.

If you're looking to determine the required mass of a substance to achieve a given molarity:

1. With the molar mass concentration known, enter the Volume of solution that you want to prepare.

2. The calculator will return the Mass of substance needed to achieve the desired molarity and volume of solution.

3. You could also use this tool the other way around. With the mass concentration and mass of the substance, the calculator can determine the volume of the solution.

Gabriela Diaz
Molar mass
g/mol
Concentration
g/mL
Molarity
M
Mass of substance
g
Volume of solution
liters
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