Calculate ratio from two numbers
If you need to generate the ratio of two numbers to each other (e.g. 4:3, 16:9, etc.), you can do using division, the GCD function, and concatenation. In the generic form of the formula (above) num1 represents the first number (the antecedent) and num2 represents the second number (the consequent).
Syntax
=num1/GCD(num1,num2)&":"&num2/GCD(num1,num2)
Example
=B4/GCD(B4,C4)&":"&C4/GCD(B4,C4)
In the example, the active cell contains this formula