Percentage Calculator
One calculator for every percentage question: percent of a number, percent change, and quick add/subtract.
About this tool
What this tool does
Most "percentage calculators" only handle one type of question. This one covers the five you actually run into: finding a percentage of a number, figuring out what percent one number is of another, calculating percent increase or decrease between two values, and adding or subtracting a percentage from a base amount (handy for tax, tips, markups, or discounts).
Who it's for
Students checking homework, shoppers working out a discount before checkout, anyone comparing a pay raise or a price hike, or a small business owner marking up a wholesale cost. Pick the calculation type from the dropdown and the two input fields relabel themselves so you always know exactly what to type.
How to use it
- Choose the calculation type from the dropdown — the field labels update to match.
- Enter your two numbers. Results update instantly as you type, no "Calculate" click required (though the button is there too).
- Copy the result and formula with one click to paste into an email, spreadsheet, or homework answer.
Real-world examples
A $150 jacket is 20% off — select "Subtract X% from Y", enter 20 and 150, and you get $120 instantly. Your rent went from $1,200 to $1,350 — use "Percentage change" to see it's an 12.5% increase. You scored 42 out of 50 on a test — "X is what percent of Y" tells you that's 84%.
Frequently asked questions
How do you calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For 20% of 150: (20 ÷ 100) × 150 = 30.
What's the formula for percent change?
(New value − Original value) ÷ |Original value| × 100. A negative result means a decrease.
How do I add a percentage to a number, like sales tax?
Multiply the base amount by the percentage as a decimal, then add it back to the original amount — that's exactly what the "Add X% to Y" mode does for you.
Can I calculate a percentage decrease, like a discount?
Yes — use "Subtract X% from Y" with your discount percentage and the original price to get the final price directly.
Is this the same as a percent-off calculator?
Yes, that's exactly what the subtract mode does, along with four other percentage calculations in the same tool.