Percentage Increase Formula
The percentage increase formula is used to compare the growth in two quantities with different initial values. For example, consider the following two businesses.
Initial Investment  Final Valuation of the Business  

Business1  $10,000  $15,000 
Business2  $30,000  $35,000 
We can see that both businesses increased by $5,000. Does this mean that they are growing at the same rate? No, because the growth has to be compared with the initial value. We use the percentage increase formula for this.
What Is the Percentage Increase Formula?
The percentage increase formula is the ratio of the increase in the quantity to its initial value multiplied by 100. Since the percentage has to be a positive quantity, we take the absolute value of the initial value. i.e.,
Percentage increase = Quantity Increase / Initial value x 100
From the previous example,
Increase in business1 = 15000  10000 = $5000.
Increase in business2 = 35000  30000 = $5000.
Let us calculate the percentage increase in each of business1 and business2.
Percentage increase in business1 = (5000 / 10000 ) * 100 = 50%
Percentage increase in business2 = (5000 / 30000 ) * 100 = 16.67%
It means that the business1 is growing more rapidly.

Example 1: The price of Ken's toy car was increased from $15 to $20. Find its percentage increase using percentage increase formula.
Solution:
To find: Percentage increase in the price of the toy car.
The initial value of the car = $15.
The final value of the car = $20.
The increase in the value = 20  15 = $5.
Using the percentage increase formula,
Percentage increase = (Increase in the height /  Initial value of the height  ) × 100
= (5 / 15) × 100
= (5 / 15) × 100
= 33.33%
Answer: Percentage increase in the toy car = 33.33%.

Example 2: The height of a tower was increased from 30 ft to 50 ft. Find the percentage increase in the height of the tower.
Solution:
To find:
Percentage increase in the height of the tower.
The initial height of the tower = 30 ft.
The final height of the tower = 50 ft.
The increase in the height = 50  30 = 20 ft.
Using the percentage increase formula,
Percentage increase = (Increase in the height /  Initial value of the height  ) * 100
= (20 / 30) * 100
= (20 / 30) * 100
= 66.67%
Answer: Percentage increase in the height of the tower = 66.67%.