Enter the quantity of the first isotope and the quantity of the reference isotope into the Isotope Ratio Calculator. The calculator will evaluate and display the Isotope Ratio. 

Isotope Ratio Formula

The following formula is used to calculate the Isotope Ratio. 

ISR = I / RI 

  • Where ISR is the Isotope Ratio
  • I is the quantity of the first isotope 
  • RI is the quantity of the reference isotope 

How to Calculate Isotope Ratio?

The following example problems outline how to calculate Isotope Ratio.

Example Problem #1:

  1. First, determine the quantity of the first isotope. 
    • The quantity of the first isotope is given as: 6.
  2. Next, determine the quantity of the reference isotope. 
    • The quantity of the reference isotope is provided as: 2.
  3. Finally, calculate the Isotope Ratio using the equation above: 

ISR = I / RI 

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

ISR = 6 / 2  = 3:1


Example Problem #2: 

For this problem, the variables required are provided below:

quantity of the first isotope = 7

quantity of the reference isotope = 4

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

ISR = I / RI  = ?