Percentage Calculator
Calculate percentages instantly. Free, no signup.
How It Works
Enter values in any of the three calculators above. Results update instantly as you type — there is no button to click. The first finds a percentage of a number, the second finds what percent one number is of another, and the third finds the percentage change between two values. All calculations run in your browser.
The Three Percentage Formulas
Each calculator uses one of these standard formulas:
| Question | Formula | Example |
|---|---|---|
| What is P% of N? | N × P ÷ 100 | 20% of 150 = 30 |
| X is what % of Y? | X ÷ Y × 100 | 30 of 150 = 20% |
| % change from A to B | (B − A) ÷ A × 100 | 80 to 100 = +25% |
Common Uses
Percentages come up constantly: working out a discount or sales tax, checking a tip, tracking a price or salary increase, grading a test score, or comparing figures in a report. Use the change calculator for growth and decline — a positive result is an increase and a negative result is a decrease.
Frequently Asked Questions
How do I calculate what percent of a number?
Use the first calculator: enter the percentage and the number, for example 20% of 150. It multiplies 150 by 0.20 to give 30. The result updates instantly as you type, with no button to press.
How do I find what percentage one number is of another?
Use the second calculator, which answers X is what % of Y. Divide the part by the whole and multiply by 100, so 30 out of 150 is 20%. Enter both numbers and the percentage appears immediately.
How do I calculate percentage change or increase?
Use the third calculator, % change from one value to another. It subtracts the old value from the new, divides by the old value, and multiplies by 100. A rise from 80 to 100 shows +25%, and a drop shows a negative percentage.
How do I calculate a percentage in my head?
Find 10% by moving the decimal one place left, then scale it: 10% of 250 is 25, so 20% is 50 and 5% is 12.5. For 15%, add the 10% amount to half of it. This calculator gives the exact figure to check your estimate.
Are my numbers sent anywhere?
No. Every calculation runs in your browser as you type, so nothing you enter is uploaded or stored on a server.