Percentage Calculator
Calculate percentages and ratios
%
Mastering Percentage Calculations
Percentage Fundamentals
Key Formulas
- X% of Y: Y × (X/100)
- X is what % of Y: (X/Y) × 100
- Percentage Change: [(New - Original)/Original] × 100
- Percentage Points: Difference between two percentages
Conversion Chart
| Percentage | Decimal | Fraction |
|---|---|---|
| 25% | 0.25 | 1/4 |
| 50% | 0.50 | 1/2 |
| 75% | 0.75 | 3/4 |
| 100% | 1.00 | 1/1 |
Calculation Methods
1
Finding X% of Y
Formula: Result = Y × (X/100)
Example: Calculate 18% of 250
- Convert percentage to decimal: 18/100 = 0.18
- Multiply by base number: 250 × 0.18
- Final result: 45
Practical Applications
- Calculating sales tax (e.g., 7% tax on $500 purchase)
- Determining tips (15-20% of restaurant bill)
- Calculating interest rates
2
Finding What Percent X is of Y
Formula: Percentage = (X/Y) × 100
Example: 35 is what percent of 140?
- Divide numbers: 35 ÷ 140 = 0.25
- Convert to percentage: 0.25 × 100 = 25%
- Interpretation: 35 is 25% of 140
Common Use Cases
- Test score calculations (e.g., 42/50 correct = 84%)
- Market share analysis
- Progress tracking
3
Advanced Percentage Operations
Percentage Increase/Decrease
Formula: Change% = [(New - Original)/Original] × 100
Example: Price increased from $80 to $100 → (20/80)×100 = 25% increase
Compound Percentages
Formula: Final = Initial × (1 ± Rate)n
Example: $1000 at 5% annual interest for 3 years → 1000 × 1.05³ = $1157.63
Percentage Calculation FAQs
Can percentages exceed 100%?
Yes! Percentages over 100% indicate values greater than the original whole. Example: 150% of 80 = 120
How to subtract percentages?
Multiply by (1 - percentage/100). Example: Subtract 20% from 150 → 150 × 0.80 = 120
Expert Calculation Tips
Decimal Conversion Guide
| 1% | 0.01 | ÷ 100 |
| 10% | 0.10 | ÷ 10 |
| 25% | 0.25 | ÷ 4 |
Common Percentage Values
- 50% = Halving
- 100% = Original amount
- 200% = Double
- 500% = Quintuple