Find a percentage
Use "What is X% of Y?" for tips, taxes, commissions, and portions of a total.
The percent is easy.
The wording is not.
Choose the question that sounds like yours, enter the numbers, and get the result with a short explanation instead of a mystery formula.
Your numbers stay in this browser. Every percentage is calculated locally with no saved history.
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What are you trying to find?
The selected question is remembered. Entered numbers are not.
The question type is remembered. Your numbers disappear when the page closes.
No formula guessing01 02 03
Pick the sentence that fits.
Compare part to whole
Use "X is what percent of Y?" when you know the amount and need its share.
Measure a change
Compare old and new values to see the increase or decrease relative to where you started.
Percentage questions.
How is percent change calculated?
The difference between the new and starting values is divided by the absolute starting value, then multiplied by 100.
Why can percent change be greater than 100%?
If a value more than doubles, its increase is greater than 100%. Moving from 40 to 100 is a 150% increase.
What happens when the starting value is zero?
Standard percent change is undefined when the starting value is zero, so the calculator explains that instead of inventing a number.
Does the calculator round?
It displays practical precision while keeping the full JavaScript number during the calculation.