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Molality Calculator

Enter the solute and solvent concentration to calculate the molality of solution through this calculator. Also, you can use advanced mode to calculate molarity from given molality.


mole (mol)

millimole (mmol)

micormole (µmol)

nanomol (nmol)

picomol (pmol)

micrograms (µg)

milligrams (mg)

grams (g)

decagrams (dag)

kilograms (kg)

ounces (oz)

pounds (lbs)

mol / micrograms (µg)

mol / milligrams (mg)

mol / grams (g)

mol / decagrams (dag)

mol / kilograms (kg)

mol / ounces (oz)

mol / pounds (lbs)

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This free molality calculator uses the molality formula to calculate concentration of solution. Many times when carrying out a chemical reaction in a lab, you are confused due to the actual concentrations of the solute or solvent used in the solution.

Let’s move ahead and discuss the concept of molality in brief detail!

What Is Molality?

In terms of chemical analysis:

“Molality is the concentration of solute mass per kilogram of the solvent”

What Is The Formula For Molality?

You can calculate molality by using the following molality formula:

Molality (m) = Moles of Solute/Kilograms of Solvent

Our free molality calculator also makes use of the same molality equation to determine the concentration in terms of solvent mass.

Molality vs Molarity: What’s The Difference?

Both of these chemical properties are quite similar. But due to one major difference among the two, there are daughter differences too. Let’s throw a light on them by going through the following table:



It is concentration of solute per kilogram of the solvent (Mass)

It is the concentration of solute per thousand litres of the solution (Volume)

Molality is expressed in the units of moles per kilogram (mol/kg)

Molarity is represented in the units of moles per litres (mol/L)

It is denoted by the symbol M

You can denote this parameter by the m or b

It is independent of temperature and pressure 

Its value changes with applied pressure and temperature

Let’s move ahead and discuss the concept of molality in brief detail!

Below we have the generic expression that lets you change molality to molarity:

M = m * d / (1 + (m * W))


  • m is the molality of the solution
  • M represents the molarity of the solution
  • D is the density (Mass per unit volume that you can also determine by the use of our other density calculator).

You can resolve all these parameters by using our free molality calculator with density in a fragment of seconds.

How To Calculate Molality?

What about molality calculations of a certain solution with the help of the example? Let’s go!

Example # 01:

Suppose you have a solution of sulphuric acid (\(H_{2}SO_{4}\)) in which the volume of the solution is about 53.2 per litre of the solution. Now if the density of the solution is about 3.22g/cm^{3}, how to find molality of acid in the whole liquid mixture?


Using molality formula, we have:

1 Litre of Solution = 1000\(cm^{3}\) = 1000mL

1.329 g/cm3 times 1000 cm3 = 1329 g (the mass of the entire solution)

1329 g minus 571.4 g = 757.6 g = 0.7576 kg (the mass of water in the solution)

571.4 g / 98.0768 g/mol = 5.826 mol of H2SO4

5.826 mol / 0.7576 kg = 7.690 m

You can also verify the results by using this free molality to molarity calculator.

How Molality Calculator Works?

Let’s go through the guide below to know how you can use this molality formula calculator to calculate molality in a couple of taps!


  • Select “Simple” if you wish to calculate different molality related entities for a solution. If in case you want to find molality from molarity, select “Advanced
  • After you are done with your selection, it’s time to put in the required parameters in their designated fields. So go for it!
  • Don't forget to select the units of each parameter from respective lists
  • At last, hit the calculate button to calculate molality


The free molarity to molality calculator does the following computations:

  • Molality of solution (Either simply or by using molarity and density)
  • Mass of solute
  • Mass of solvent


Does density matter in molality?

Yes, as for any concentrated solution, the molarity and molality are not the same. And if you want to calculate molality, you need to figure out the density of the solution so that the property could be judged properly. In case you feel a hurdle, try our free molality calculator for instant calculations.

Does molality change with dilution?

No, as molality does not depend upon the volume of the solution, so it does not change with any kind of dilution variation. You can also judge it by using a molality to molarity calculator.

Is molality a concentration?

Molality is a unit of concentration just like molarity. And for its calculations, you may use this molality to molarity calculator.

How does molality relate to freezing point?

Molality of any solution is always directly proportional to the freezing point of the solute and not the whole solution. This is because freezing points of the solutions are always less than that of the solvent. You can also analyse such a change by using the molality equation’s corresponding expressions.

How does molality affect boiling point?

Being in the direct relationship, the molality rise will increase the boiling point thus lowering the melting point.

Why is molality used instead of molarity?

Molality of a solution is always preferred over molarity because it is independent of different chemical parameters like pressure and temperature as aforementioned.

Does the molarity continue to change Why or why not?

No, the molality of a solution is always the same. No matter how much quantity of the solution you are experimenting on,its value remains the same. For instance, you can let this molality calculator confirm this fact for you.

Who discovered molality?

The concept of molality was proposed by the famous chemists Lewis and M. Randall, in the year 1923.

Why is molality used in colligative properties?

The reason why molality is being used in colligative properties is that it does not change with increasing volume and helps you to calculate molar fractions. Moreover, you can also use a molar fraction calculator if you are interested in calculating the fractions of moles used in refining a chemical product during synthesis.


The molality is a very important parameter considered as it helps you to explore solution properties just like vapour pressure and temperature changes. And this is why we have designed this free molality calculator to examine ideal characteristics of a solution so as to avoid any error in the calculations.


From the source of Wikipedia: Molality, Origin, Usage considerations, Advantages, Relation to other compositional quantities, Mass fraction, Mole fraction, Mass concentration, Osmolality, Relation to apparent (molar) properties

From the source of Khan Academy: Molarity calculations, Dilution, Boiling point elevation and freezing point depression

From the source of Coursehero: Molality, Measurements of Mass, Calculating Mass Given Molality

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