Percentage calculator
Four everyday percentage questions, answered the instant you type. Find a percent of a number, work out what percent one value is of another, measure a change between two numbers, or add and subtract a percentage. No formulas to remember.
Percent of a number
X is what percent of Y
Percentage change
Add or subtract a percent
What each calculator does
Percent of a number
Use it for tips, discounts, tax and commissions. "What is 15% of 200?" gives 30 — handy any time you need a slice of a total.
One number as a percent
Turn a raw figure into a share. "30 is what percent of 200?" returns 15% — perfect for test scores, progress and proportions.
Change and add-on
Measure growth or a drop between two numbers, or apply a markup or markdown to a starting value in one step.
Where percentages come up
Shopping and dining
Split a bill, add a tip, or check whether a "40% off" sale is really the better deal. The add-or-subtract card handles sales tax and discounts without extra steps.
Money and work
Compare this month's revenue to last, size up a pay rise, or convert a part of a budget into a percentage of the whole. The change card labels every result as an increase or decrease.
Nothing tracked
All four calculators run locally in your browser. The numbers you enter are never sent anywhere, and there's no account or cookie wall to get past.
The percentage basics
A percentage is simply a fraction out of one hundred. Ten percent means ten per hundred, or 0.10 as a decimal. Every calculation on this page comes down to converting between that decimal form and the numbers you care about, which is why the same idea covers tips, discounts, growth rates and test scores alike.
Finding a percent of a number
Multiply the number by the percentage written as a decimal. Fifteen percent of 200 is 0.15 × 200 = 30. This is the operation behind a restaurant tip, a sales-tax line, or a commission on a sale.
Expressing one number as a percent of another
Divide the part by the whole and multiply by one hundred. If you scored 30 out of 200, that's 30 ÷ 200 × 100 = 15%. The same method turns any two related figures into a clear proportion.
Percentage change vs percentage points
Percentage change compares a new value to an old one: going from 100 to 150 is a 50% increase because the gain of 50 is half of the original 100. Note that a rise from 20% to 30% is a 10 percentage-point move but a 50% increase — the two ideas are easy to mix up, so it helps to be clear which you mean.
Frequently asked questions
How do I calculate a percentage of a number?
Write the percentage as a decimal and multiply. For 15% of 200, use 0.15 × 200 = 30. The first card on this page does it for you as you type.
How do I work out percentage change?
Subtract the old value from the new one, divide by the old value, then multiply by 100. From 100 to 150 that's (150 − 100) ÷ 100 × 100 = 50%. A positive result is an increase, a negative one a decrease.
What's the difference between percent and percentage points?
Percentage points measure the gap between two percentages directly, while percent change measures that gap relative to the starting value. Moving from 20% to 30% is 10 points but a 50% increase.
How do I add tax or a discount?
Use the fourth card. Choose "plus" for tax or a markup and "minus" for a discount, then enter the rate. For example, 200 minus 10% returns 180.
Can it handle decimals and negative numbers?
Yes. Every field accepts decimals, and the change calculator handles negative starting values correctly, flagging whether the result is an increase or a decrease.
Is anything I type stored?
No. The calculators run entirely in your browser. Nothing is uploaded, saved or tracked, and there is no sign-up.