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Atomic Mass Calculator

Atomic Mass Calculator

Enter the number of protons (Z) and neutrons (N) to calculate the atomic mass

Number of Protons (Z)

Number of Neutrons (N)


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The atomic mass calculator determines the atomic mass along with its unit and symbol. For a given element, it is the quickest and easy way to find the combined mass of proton, electron, and neutron in an atom.

What is Atomic Mass?

Atomic mass accounts for the overall mass of an atom, considering its protons, neutrons, and electrons. It is expressed in the atomic mass unit (amu) and expressed by the symbol “U”.

However, the electron is 1,836 times lighter than a proton therefore, their contribution to the overall mass of most atoms is minimal.

Atomic Mass Formula:

Atomic mass is expressed in atomic mass units (u), also known as Daltons (Da). An atomic mass unit (Dalton) is 1/12 of the mass of a carbon atom. Therefore, the unit of atomic mass is \( 1.66 \times 10^-27 kg \).

Atomic mass (u) = number of neutrons + number of protons


\(\ A = N + Z\)


  • A = atomic mass number
  • Z = number of protons
  • N = number of neutrons

Why does an Atom Need a Neutron?

As we know the atom has a neutral charge and it require neutrons for some reason: to add mass to the nucleus and stabilize it against the repulsive force between positively charged protons. The atomic mass calculator makes their determinations easy.

However, all the positive charges are concentrated in the center of the proton. Just as charges repel, there is a force that tries to destroy the core or nucleus of an atom. The opposite of this force is the strong nuclear force that exists between neutrons and protons.

Therefore, the total amount of strong nuclear attraction can be increased by adding neutrons to prevent atomic destruction. However, the Mole Calculator helps you to calculate the number of moles of a substance based on the molecular weight and the quantity of that material.

Steps To Use The Calculator:

The atomic weight calculator determines the atomic mass by the following steps:


  • Enter number of protons (Z) and number of neutrons (N)
  • Press the “calculate” button


  • Atomic mass number
  • SI units of atomic mass
  • Atomic Symbol