Percentage Calculator
Five common percentage questions in one tool. Pick the question you need, enter two numbers and get the answer with the formula used, so you can check it or explain it to someone else.
How to use the Percentage Calculator
- Choose the type of calculation, for example "X% of Y" or "% change A → B".
- Enter the two values.
- Press Calculate to see the answer, a plain-English sentence and the formula.
- Copy the sentence to paste it into a message or report.
Features
- X% of Y, X is what % of Y, and percentage change from A to B
- Increase or decrease a value by a percentage
- Shows the formula and the difference between values
- Handles negative starting values for percentage change
Benefits
- Answer price, grade, growth and statistics questions in seconds
- Avoid the common mistake of dividing by the wrong number in percentage change
Frequently asked questions
How is percentage change calculated?
Percentage change = (new − old) ÷ |old| × 100. Going from 80 to 100 is a 25% increase; going from 100 back to 80 is a 20% decrease.
Why is a 20% increase followed by a 20% decrease not the same number?
The second percentage is applied to a larger base. 100 + 20% = 120, and 120 − 20% = 96.
Can I calculate change from zero?
No. A percentage change from zero is undefined because it would mean dividing by zero, so the calculator asks for a non-zero starting value.
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