What is a percentage?
A way to show a part of a whole out of 100, written with %. For example, 25% means 25 per hundred — one quarter of the total.
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FAQs
How do I find X% of a number?
Use “Calculate X% of Y”. Enter the percent and the amount — e.g. 15% of 200 is 30. Formula: (percent ÷ 100) × amount.
How do I find what percent one number is of another?
Use “X as a percentage of Y”. Enter the part and the whole — e.g. 25 of 200 is 12.5%. Formula: (part ÷ whole) × 100.
What is percentage change?
The percent a value went up or down from a start to an end. Use “Percentage change”; positive means increase, negative means decrease.
When are percentages useful?
Any time you compare parts to a whole: discounts, tips, tax, markups, grades, or growth rates. They make different-sized totals easy to compare.
Why do I see a divide-by-zero error?
The whole (or starting value) cannot be zero. Enter a non-zero number in that field and the result will update.
Is my data stored or sent anywhere?
No. Everything runs in your browser. Nothing you type is uploaded or saved on a server.