Use this free percentage calculator for three common calculations: finding a percentage of a number, determining what percentage one number is of another, and calculating percentage change.
How Percentages Work
A percentage represents a number as a fraction of 100. For example, 25% means 25 out of every 100, which is equivalent to 0.25.
Percentage Formulas
Percentage of a number: (percentage ÷ 100) × number
What percent one number is of another: (part ÷ whole) × 100
Percentage change: ((new value − original value) ÷ |original value|) × 100
Examples
20% of 150 is 30. If 30 is compared with 150, then 30 is 20% of 150. If a value increases from 100 to 125, the percentage increase is 25%.
Common Uses
Percentage calculations are commonly used for discounts, taxes, tips, grades, financial changes, business metrics, statistics and everyday comparisons.
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Understanding Percentage Calculations
A percentage expresses a number as a fraction
of 100. Percentages are commonly used to
calculate discounts, taxes, interest rates,
exam scores, and changes in prices.
How to Calculate a Percentage
To find a percentage of a number, multiply
the number by the percentage and divide by 100.
Example: What is 15% of 200?
(15 / 100) × 200 = 30.
Therefore, 15% of 200 is 30.
How to Calculate Percentage Increase
Percentage increase =
((New Value - Original Value) /
Original Value) × 100.
Example: A product increases from $80 to $100.
The increase is $20, representing a 25% increase.
How to Calculate Percentage Decrease
Percentage decrease =
((Original Value - New Value) /
Original Value) × 100.
Example: A product decreases from $100 to $75.
The decrease is $25, representing a 25% decrease.
Percentage vs. Percentage Points
If an interest rate rises from 4% to 6%,
it increases by 2 percentage points.
This is also a 50% relative increase
compared with the original 4% rate.
Frequently Asked Questions
How do I calculate a 20% discount?
Multiply the original price by 0.20 and
subtract the result. For a $50 item,
the discount is $10 and the final price is $40.
Can a percentage exceed 100%?
Yes. For example, 150% of 200 equals 300.
Percentages greater than 100% are common
when describing growth or comparisons.
What happens if the original value is zero?
The standard percentage-change formula is
undefined when the original value is zero
because division by zero is not possible.