Percentage Calculator
Calculate percentages easily. Find percentage of a number, increase/decrease, percentage difference and more.
1. Choose calculation type
Percentage of a number
What is X% of Y?
Number is what percent of another
X is what % of Y?
Percentage increase
Increase Y by X%
Percentage decrease
Decrease Y by X%
Percentage difference
Find the % difference between two numbers
Reverse percentage
If X is Y%, what is 100%?
2. Enter values
%
3. Result
25% of 80 =
20
How it’s calculated
Your data stays private
Percentages are calculated locally in your browser. Nothing is uploaded or stored on a server.
Learn more about privacy →Quick examples
Formula
Where:
Percentage — the percent you want to take
Number — the original amount
Result — X% of Y
About percentage
The word “percent” comes from Latin per centum — by the hundred. A percentage is a ratio times 100, which is why 25% of 80 is 20 and why “20 is what percent of 80?” is 25. This page is a live six-mode calculator, not a single formula with a Generate button. Percent of a number is X/100 × Y. “Is what percent” is 100 × X/Y (Y cannot be zero). Increase and decrease apply X% to Y. Percentage difference is the relative gap between two numbers using their average in the usual school formula. Reverse percentage answers “if this value is Y%, what is 100%?” — 20 is 25% means the whole is 80.
Worked example: a price of 80 with 25% off is a discount problem (use Discount Calculator). A test score 18 of 24 is “is what percent.” A raise from 50,000 to 55,000 is percent increase, not the same as percent difference. Reverse percentage is the trap when a shop says “sale price is 70% of list” and you need list.
Common mistakes: mixing percent points with percent change; dividing by the wrong base; treating margin as markup (Profit Margin Calculator). Limitations: no compounding, no tax tables, no currency. All math stays in this tab. Related: Discount, Tip, Loan, GPA.
How to use
Choose a type
Pick the calculation: percent of a number, increase, decrease, difference, or reverse.
Enter values
Type the numbers. The result updates as you type.
Copy the result
Copy the number, or tap a quick example to fill the fields.
Stays private
All math runs in this tab. Nothing is uploaded.
More math tools
Discount Calculator
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Profit Margin Calculator
From cost and selling price, see profit, margin on revenue, and markup on cost. Margin and markup are not the same number. Math stays in the browser.
Loan Calculator
Estimate a fixed monthly payment, payment count, total paid, and total interest from principal, APR, and years. Zero APR is allowed. This is not a lender quote.
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Find completed years, leftover months, and leftover days between a birth date and an as-of date. The civil calendar runs in your browser — nothing is uploaded.
Percentage Calculator FAQ
Choose Percentage of a number, then enter the percent and the number — for example 25% of 80. The result updates as you type. Tap a quick example if you want a filled-in check.
Reverse percentage finds the original 100% amount when you know a part and the percent it represents. If 20 is 25%, the original value is 80.
No. Every mode runs locally in your browser. Nothing is uploaded or stored on a server.