Percentage Calculator
Find a percent of a number, what percent one value is of another, and percentage change — instantly.
The easy way to calculate percentages
The Percentage Calculator handles the three percentage questions people ask most often: what is X% of a number, what percent one number is of another, and the percentage increase or decrease between two numbers. Type your values and the answers update instantly. There is no formula to remember and no risk of a misplaced decimal — the calculator does the math for you, accurately, every time.
Three calculators in one
1. What is X% of Y?
Use this when you want a portion of a number — a tip, a discount, a tax amount, or a commission. For example, 10% of 250 is 25. The formula is simply (X ÷ 100) × Y.
2. X is what percent of Y?
Use this to express one number as a percentage of another — a test score, a completion rate, or a market share. For example, 45 out of 180 is 25%. The formula is (X ÷ Y) × 100.
3. Percentage increase or decrease
Use this to measure change over time — a price rise, a salary bump, or a drop in expenses. Going from 120 to 150 is a 25% increase. The formula is ((new − old) ÷ old) × 100. A positive result is an increase; a negative result is a decrease.
Real-world examples
| Question | Calculation | Answer |
|---|---|---|
| 15% tip on a $80 bill | (15 ÷ 100) × 80 | $12 |
| Scored 38 out of 50 | (38 ÷ 50) × 100 | 76% |
| Price rose $50 → $65 | ((65 − 50) ÷ 50) × 100 | +30% |
| 20% off a $120 item | 120 − (20 ÷ 100 × 120) | $96 |
How to use it
- Pick the calculator that matches your question.
- Type your numbers into the fields.
- Read the answer instantly — no button to press.
Percentages in everyday life
Percentages are everywhere: sales tax, restaurant tips, store discounts, interest rates, grades, statistics, and business metrics. Being able to calculate them quickly helps you check a bill, compare deals, understand a report, or set a budget. This calculator keeps all three common percentage operations on one page so you do not have to switch tools or look up formulas.
A quick mental-math tip
To find 10% of any number, just move the decimal point one place to the left (10% of 250 is 25.0). From there you can build other percentages: 5% is half of 10%, 20% is double, and 15% is 10% plus 5%. The calculator above is faster and exact, but these tricks are handy when you are away from a screen.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 10% of 250 is (10 ÷ 100) × 250 = 25.
How do I work out what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 45 of 180 is (45 ÷ 180) × 100 = 25%.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100. From 120 to 150 is a 25% increase.
Is this percentage calculator free?
Yes, completely free, with no sign-up. It runs in your browser and updates instantly as you type.