Calculators
Percentage Calculator Guide: Percent Of, Increase, Decrease, and Change
Understand common percentage calculations for discounts, growth, comparisons, school work, and everyday numbers.
Percentage Calculator
Calculate a percentage of a number.
Percent of a number
The most common percentage question is finding a percent of a number. For example, 20 percent of 50 is 10. This is useful for discounts, fees, grades, and quick estimates.
A calculator helps avoid decimal mistakes, especially when values are not round numbers.
Percentage increase and decrease
Percentage change compares an old value with a new value. It is commonly used for prices, traffic, revenue, growth, and measurements.
The direction matters. Increasing from 100 to 120 is a 20 percent increase, while decreasing from 120 to 100 is not the same percentage in reverse.
Use labels to avoid confusion
Clearly label the original value, new value, percentage rate, and result. Many mistakes happen when the starting value and final value are swapped.
For shopping, remember that discounts, tax, and tips may be applied in different orders depending on the situation.
FAQ
How do I find 20 percent of a number?
Multiply the number by 0.20. A calculator can do the conversion from percent to decimal for you.
What is percentage change?
It is the change between an old value and a new value expressed as a percent of the old value.
Why do increase and decrease not reverse perfectly?
Because each percentage is based on a different starting value.
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