Enter the number of protons in the isotope and the number of neutrons in the isotope into the Relative Mass Calculator. The calculator will evaluate and display the Relative Mass.

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## Relative Mass Formula

The following formula is used to calculate the Relative Mass.

**RM = P + N**

- Where RM is the Relative Mass (amu)
- P is the number of protons in the isotope
- N is the number of neutrons in the isotope

## How to Calculate Relative Mass?

The following example problems outline how to calculate Relative Mass.

Example Problem #1:

- First, determine the number of protons in the isotope.
- The number of protons in the isotope is given as: 5.

- Next, determine the number of neutrons in the isotope.
- The number of neutrons in the isotope is provided as: 7.

- Finally, calculate the Relative Mass using the equation above:

RM = P + N

The values given above are inserted into the equation below and the solution is calculated:

RM = 5 + 7 = 12.00 (amu)

Example Problem #2:** **

For this problem, the variables needed are provided below:

number of protons in the isotope = 8

number of neutrons in the isotope = 3

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer.

RM = P + N** = ?**