Percentage Calculator
This free percentage calculator handles the three questions people actually ask: what a percentage of a number is, what percent one number is of another, and the percentage increase or decrease between two numbers. Pick the calculation you need and get an instant answer, with no formulas to remember.
How to Use It
- Each calculation has its own box: percentage of a number, what percent one number is of another, and percentage change.
- Enter the two numbers in whichever box answers your question.
- The result appears instantly in that box, with no submit button.
- Use as many of the three boxes as you need. They work independently of each other.
How It Works
Each of the three calculations uses a different, standard percentage formula. "X% of Y" multiplies Y by X divided by 100. "X is what % of Y" divides X by Y and multiplies by 100. "Percentage change from X to Y" subtracts X from Y, divides by X, and multiplies by 100. Whether that comes out positive or negative determines whether it's reported as an increase or a decrease.
Formulas
X% of Y = Y × (X ÷ 100)
X is what % of Y = (X ÷ Y) × 100
percentage change from X to Y = ((Y − X) ÷ X) × 100
The percentage-change calculation is the one most worth double-checking your intuition on: it's always relative to the starting value, which is why the same-sized change can produce different percentages depending on which direction you're going (see the FAQ on why a 50% increase followed by a 50% decrease doesn't bring you back to where you started).
Worked examples of each: 15% of 200 is 200 × (15 ÷ 100) = 30. 45 as a percent of 180 is (45 ÷ 180) × 100 = 25%. Going from 80 to 100 is a percentage change of ((100 − 80) ÷ 80) × 100 = 25% increase, the same 25% figure as the previous example by coincidence of these particular numbers, not because "percent of" and "percent change" are the same calculation.
Everything runs client-side in your browser. Nothing you enter is sent anywhere or stored.
Frequently Asked Questions
"X% of Y" vs. "percentage change": what's the difference?
"X% of Y" answers a direct question like "what is 15% of 200?" It's a portion of a single number. "Percentage change" instead compares two different numbers (a starting value and an ending value) and tells you how much bigger or smaller the second one is, as a percentage of the first. They're easy to mix up because both involve percentages, but they answer different questions.
What's the difference between a percentage and a percentage point?
If a rate goes from 20% to 25%, that's a 5 percentage point increase (25 minus 20), but a 25% increase in relative terms (5 is 25% of 20). Percentage points describe the raw difference between two percentages; "percent change" describes that difference relative to the starting value. Mixing these up is one of the most common statistics mistakes in news reporting.
Why is a percentage increase followed by the same percentage decrease not a net-zero change?
Because each percentage is calculated from a different base. Increasing 100 by 50% gives 150, but decreasing 150 by 50% gives 75, not 100. The second percentage was taken from the new, larger number. This is why "up 50%, then down 50%" always ends up lower than where you started.
How do I calculate a discounted sale price?
A discount is really "X% of Y" in reverse: calculate the discount amount using the "X% of Y" box (discount percentage of the original price), then subtract that from the original price yourself. For example, 20% of a $60 item is $12, so the sale price is $60 − $12 = $48.
Can I find the original price if I only know the discounted price and the discount percentage?
Yes, though it takes a small manual step this calculator doesn't do directly: if a discounted price is P after an X% discount, the original price is P ÷ (1 − X/100). A $48 price after a 20% discount means the original was 48 ÷ 0.8 = $60. This is a different formula from a plain "X% of Y" calculation, since you're working backward from the discounted total rather than forward from the original price.
Can I use this for sales tax or a tip?
The "X% of Y" box works for a quick sales tax or tip amount (tax rate or tip percentage as X, the bill as Y), but our dedicated Tip Calculator handles splitting the total between multiple people at the same time, which this generic tool doesn't.
Can "percent of" results go over 100%?
Yes, whenever the first number is larger than the second: 250 is 125% of 200, for example. That's a completely valid result; percentages aren't capped at 100, since "percent" just means "per hundred," not "a fraction of a whole."