Percentage Calculator
Calculate percentages quickly and easily. Supports percentage of a number, percentage increase/decrease, percentage difference, and more. Perfect for discounts, tips, grades, and financial calculations.
What is X% of Y?
X is what % of Y?
Percentage Increase/Decrease
Apply Percentage Change
Percentage Difference
What is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred." Percentages are used everywhere: in discounts, interest rates, statistics, grades, and more. The symbol % represents percent.
Common Percentage Calculations
1. Calculate X% of Y
Find what portion of a number a percentage represents. Useful for calculating tips, discounts, and taxes.
Example: What is 25% of 200? = (25 / 100) × 200 = 50
2. X is What % of Y?
Find what percentage one number is of another. Great for calculating completion rates, scores, and ratios.
Example: 50 is what % of 200? = (50 / 200) × 100 = 25%
3. Percentage Increase/Decrease
Calculate the percentage change between two values. Used for price changes, growth rates, and statistics.
Example: From 100 to 150 = ((150 - 100) / 100) × 100 = 50% increase
Real-World Use Cases
- Shopping & Discounts: Calculate sale prices and savings (30% off $100 = $70)
- Restaurant Tips: Calculate 15%, 18%, or 20% tips on bills
- Taxes: Add sales tax to purchases (7% tax on $50 = $53.50)
- Academic Grades: Convert scores to percentages (45/60 = 75%)
- Finance & Interest: Calculate interest rates and returns
- Business Metrics: Growth rates, profit margins, conversion rates
- Statistics: Survey results, demographics, and data analysis
- Nutrition: Daily value percentages on food labels
- Project Progress: Track completion percentages
- Salary Changes: Calculate raises and pay cuts
Percentage Examples
Item: $80, Discount: 25%
Savings: $20
Final price: $60
Bill: $45, Tip: 18%
Tip amount: $8.10
Total: $53.10
Correct: 42 out of 50
Score: (42/50) × 100
Grade: 84%
Old: $500, Increase: 10%
Increase: $50
New price: $550
Percentage Tips & Tricks
- 10% trick: To find 10%, just move the decimal point one place left (10% of 80 = 8.0)
- 5% trick: Find 10% and divide by 2 (5% of 80 = 4.0)
- 1% trick: Move decimal two places left (1% of 80 = 0.8)
- 25% = ¼: Divide by 4 for quick mental math (25% of 80 = 20)
- 50% = ½: Simply divide by 2 (50% of 80 = 40)
- 75% = ¾: Find 50% and add 25% (75% of 80 = 60)
- Double percentage: 20% of 50 = 50% of 20 (both = 10)
- Successive discounts: 20% off then 10% off ≠30% off total
Common Percentage Equivalents
| Percentage | Decimal | Fraction |
|---|---|---|
| 10% | 0.1 | 1/10 |
| 20% | 0.2 | 1/5 |
| 25% | 0.25 | 1/4 |
| 33.33% | 0.3333 | 1/3 |
| 50% | 0.5 | 1/2 |
| 66.67% | 0.6667 | 2/3 |
| 75% | 0.75 | 3/4 |
| 100% | 1.0 | 1/1 |
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. Or convert the percentage to a decimal (divide by 100) and multiply. For example: 25% of 80 = (25/100) × 80 = 0.25 × 80 = 20.
What's the difference between percentage increase and percentage difference?
Percentage increase uses the original value as the base. Percentage difference uses the average of both values as the base, giving a symmetric result regardless of which value is first.
How do I calculate reverse percentages?
If you know the final value after a percentage change, divide by (1 + percentage/100) for increase, or (1 - percentage/100) for decrease. Example: $120 after 20% increase = 120 / 1.20 = $100 original.
Can percentages be more than 100%?
Yes! Percentages over 100% represent values larger than the whole. For example, if sales doubled, that's a 100% increase. If they tripled, that's a 200% increase.
Is my data stored or sent to a server?
No, all calculations happen entirely in your browser using JavaScript. Your numbers never leave your device and are not stored anywhere.