Percentage Formula
Calculate percentages using Percentage = (Part / Whole) × 100.
Includes formulas for percentage increase, decrease, and finding the whole.
The Formula
Percentage: Percentage = (Part / Whole) × 100
Finding the Part: Part = (Percentage / 100) × Whole
Finding the Whole: Whole = Part / (Percentage / 100)
The percentage formula expresses a number as a fraction of 100.
"Percent" literally means "per hundred."
Variables
| Symbol | Meaning |
|---|---|
| Percentage | The result expressed as a value out of 100 |
| Part | The portion or amount you are measuring |
| Whole | The total or full amount |
Percentage Change
- A positive result means a percentage increase
- A negative result means a percentage decrease
Example 1
You scored 42 out of 60 on a test. What is your percentage?
Part = 42, Whole = 60
Percentage = (42 / 60) × 100
Percentage = 0.7 × 100
Percentage = 70%
Example 2
A shirt was $80 and is now $60. What is the percentage decrease?
Old Value = 80, New Value = 60
Percentage Change = ((60 - 80) / 80) × 100
Percentage Change = (-20 / 80) × 100 = -0.25 × 100
Percentage Change = -25% (a 25% decrease)
When to Use It
Use the percentage formula when:
- Calculating test scores, grades, or completion rates
- Figuring out discounts and sale prices
- Measuring percentage increases or decreases (profit, loss, growth)
- Comparing proportions across different totals