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 — 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 — 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.
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).
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.