Enter the total number of neutrons and the total number of protons into the Neutron to Proton Ratio Calculator. The calculator will evaluate and display the Neutron to Proton Ratio. 

Neutron to Proton Ratio Formula

The following formula is used to calculate the Neutron to Proton Ratio. 

NPR = N / P

  • Where NPR is the Neutron to Proton Ratio (neutrons:protons)
  • N is the total number of neutrons 
  • P is the total number of protons 

How to Calculate Neutron to Proton Ratio?

The following example problems outline how to calculate Neutron to Proton Ratio.

Example Problem #1:

  1. First, determine the total number of neutrons. 
    • The total number of neutrons is given as: 6.
  2. Next, determine the total number of protons. 
    • The total number of protons is provided as: 3.
  3. Finally, calculate the Neutron to Proton Ratio using the equation above: 

NPR = N / P

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

NPR = 6 / 3 = 2:1 (neutrons:protons)


Example Problem #2: 

For this problem, the variables required are provided below:

total number of neutrons = 8

total number of protons = 5

Test your knowledge using the equation and check your answer with the calculator above.

NPR = N / P = ?