Percentage Calculator
Calculate any percentage in seconds — free, no account required, and your numbers never leave your device. Find what X% of a number is, work out what percent one number is of another, calculate a percentage increase or decrease, or add and subtract percentages from values.
Select calculation type
What is X% of Y?
Formula used
result = (X ÷ 100) × YHow It Works
Pick your calculation type
Choose from five modes: find X% of a number, work out what percent X is of Y, calculate a percentage change, or add/subtract a percentage from a value.
Enter your numbers
Type in the two values. The input labels update for each mode so you always know which number goes where — no guessing.
Get the answer instantly
Your result appears as you type — no button to press. The formula used is shown beneath the answer so you can verify it yourself.
How to Use the Percentage Calculator
- Select the calculation type using the mode buttons at the top of the tool.
- Enter your two numbers in the labelled fields — labels change to match the selected mode.
- Read the result instantly — it updates as you type, with no button to press.
- Check the formula reference shown below the result to understand the maths.
Calculation Modes Explained
| Mode | Question answered | Formula |
|---|---|---|
| X% of Y | What is 15% of 200? | (X ÷ 100) × Y |
| X is what % of Y | 50 is what percent of 200? | (X ÷ Y) × 100 |
| % Change | What is the % change from 80 to 100? | ((New − Original) ÷ |Original|) × 100 |
| Add % | What is 200 increased by 15%? | Y + (X ÷ 100) × Y |
| Subtract % | What is 200 decreased by 15%? | Y − (X ÷ 100) × Y |
Features
- Five calculation modes: covers the most common everyday percentage problems in one place.
- Instant results: answers update as you type — no button required.
- Formula reference: the maths behind each result is shown so you can learn and verify.
- Your data stays private: all calculations run locally in your browser — nothing is uploaded or stored.
- No account required: open the page and start calculating straight away.
- Works on any device: optimised for desktop and mobile browsers.
Common Percentage Examples
| Question | Mode to use | Answer |
|---|---|---|
| What is 20% of 150? | X% of Y | 30 |
| 45 is what % of 180? | X is what % of Y | 25% |
| Price went from $80 to $100 — how much did it rise? | % Change | +25% |
| Add 10% VAT to £500 | Add % | £550 |
| 30% off a $120 item | Subtract % | $84 |
Frequently Asked Questions
How do I find what percentage one number is of another?
Select the X is what % of Y mode. Enter the smaller (or part) number as X and the total as Y. The calculator divides X by Y and multiplies by 100 to give you the percentage.
What is the formula for percentage change?
Percentage change = ((New − Original) ÷ |Original|) × 100. A positive result means an increase; a negative result means a decrease. The tool shows this formula beneath every result.
How do I calculate a discount?
Select the Subtract % mode. Enter the discount percentage as X and the original price as Y. The result is the discounted price after removing that percentage.
How do I add VAT or sales tax to a price?
Select the Add % mode. Enter the tax rate (e.g. 20 for 20% VAT) as X and the pre-tax price as Y. The result is the total price including tax.
Is my data stored or sent to a server?
No. Everything runs locally in your browser using JavaScript. The numbers you enter are never sent to or stored on any server.
What's the difference between percentage change and percentage point change?
A percentage change is relative: going from 10% to 12% is a 20% increase in the rate. A percentage point change is absolute: going from 10% to 12% is a 2 percentage point change. This calculator computes percentage change (relative).