# How to calculate atomic mass

Atomic mass is the sum of all of the protons, electrons, and neutrons in an atom. This is also sometimes used to talk about the average mass of a group of atoms. Neutrons and Protons make up most of the mass of the atom, in fact, electrons are so light that they aren’t used in mass calculations at all. The following article explains how to calculate that mass.

## Atomic Mass calculator

Calculate the atomic mass of any atom, in atomic mass units (amu) by adding the total number of neutrons and total number of protons.

To determine the number of protons in neutrons in an item you first need to get a periodic table. For example, take carbon, which has an element symbol of C. If you look on the periodic table you can see it has an atomic number of 6. The atomic number is NOT the same as atomic mass, it’s the number of protons in the atom.

Now you need to determine the number of neutrons in the atom. For Carbon this is 7 neutrons. Add them together and you get the atomic mass.

The atomic mass of every element is usually displayed directly on the periodic table. But what if you need to find the atomic weight of of a group of atoms? For that you need to multiply the atomic weights of each atom in the group by the total number of that atom, then divide by the total number of atoms to get the average weight.