Question

How to calculate percentage difference between two values?

Answer 1

To calculate the percentage increase:

First: work out the difference (increase) between the two numbers you are comparing.

Increase = New Number - Original Number

Then:  divide the increase by the original number and multiply the answer by 100.

% increase = Increase ÷ Original Number × 100.

If your answer is a negative number then this is a percentage decrease.

To calculate percentage decrease:

First: work out the difference (decrease) between the two numbers you are comparing.

Decrease = Original Number - New Number

Then: divide the decrease by the original number and multiply the answer by 100.

% Decrease = Decrease ÷ Original Number × 100

Answer 2

Let us assume two values, a and b

a = 50, b = 70

Let us calculate the percentage difference that exists between the two values.

Formula for percentage difference is given below:

% difference      =  $(\frac{\frac{\mid{a-b}\mid}{a+b}}{2})*100$                                 Here a= 50 and b=70

=  $(\frac{\frac{\mid{a-b}\mid}{a+b}}{2})*100$

   = $(\frac{\frac{\mid{50-70}\mid}{50+70}}{2})*100$

                              = $(\frac{\frac{\mid{-20}\mid}{120}}{2})*100$  

                                                         = $\frac{20}{60}* 100$  

                                                         = $\frac13$*100  

                                                        = 33.33%