Created By : Rina Nayak

Reviewed By : Phani Ponnapalli

Last Updated : Apr 27, 2023

Equivalent weight calculator is a tool to know the equivalent weight of a chemical reaction. All you need is to give the molecular weight of acid, basicity of acid , unknown value as X and tap on the calculate button to avail the output.

Molecular Weight of Acid(Mw)
Basicity of Acid(B)
Equivalent Weight of Acid(Ew)

Equivalent Weight - Definition

The equivalent weight of a solution can be defined as the ratio of the molecular weight to the valency of the solute. The number of reactants that completely react with each other in a chemical reaction is called the equivalent weight.

Equivalent Weight Formula

Equivalent weight is a division of molecular weight to valency. The Equivalent weight or Equivalent masses of acid,bases, and salt may be calculated by the formula

Equivalent Weight = Molecular Weight / valency

Rearranging the above formula we can find the other parameters too i.e. Molecular weight =equivalent weight * valency

Valency=molecular weight /equivalent weight

  • Equivalent weight of an acid = molecular weight of acid / basicity
  • Equivalent weight of a base = molecular weight of base / acidity
  • Equivalent weight of a salt=molecular weight of a salt/valency of metal ions
  • Equivalent weight of an acid or base, an element is always less than its molecular weight .

Examples on How to Calculate Equivalent Weight

Example 1: Calculate the Equivalent Weight of Chemical Compound Aluminium Chloride?


Alcl33 ➝ Al+3 +3cl-

Atomic Weights of atomic weight of aluminium is 26.98 and atomic weight of chlorine is 35.4

The number of positive charge on aluminium cation is 3. Therefore valency is 3

Molecular weight of Aluminium Chloride = 133.34 g/mol

Equivalent weight of Aluminium chloride salt = 133.34/3 = 44.44

Example 2: Find the Equivalent Weight of Chemical Compound Silver Carbonate?


Ag2CO3 ➝ 2Ag++Co3-

atomic weight of silver is 107.86

atomic weight of carbon is 12

atomic weight of oxygen is 16

Total Positive charge of silver Cation is 2.

Molecular weight of silver carbonate = 275.75 g/mol

Equivalent Weight of silver carbonate salt = 275.75/2 = 137.87


FAQ’s on Equivalent Weight Calculator

1. What is meant by gram equivalent?

The quantity of an element, group or compound that has a mass in grams equal to the equivalent weight.

2. What is meant by molecular weight?

Molecular Weight is nothing but the Sum of the atomic masses of all atoms in a molecule. Its units are kilogram/mole.

3. What is meant by Valency?

Valency is determined by the number of electron that an atom or group can lose, add or share. Ex: One atom of nitrogen combines with three atoms of nitrogen to form ammonia(NH3) gas. So the valency of nitrogen is 3.

4. What is the formula for Equivalent Weight?

The Formula for Equivalent Weight is Equivalent Weight = Molecular Weight/Valency.