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

PercentageDecimalFraction
25%0.251/4
50%0.501/2
75%0.753/4
100%1.001/1

Calculation Methods

1

Finding X% of Y

Formula: Result = Y × (X/100)

Example: Calculate 18% of 250

  1. Convert percentage to decimal: 18/100 = 0.18
  2. Multiply by base number: 250 × 0.18
  3. 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?

  1. Divide numbers: 35 ÷ 140 = 0.25
  2. Convert to percentage: 0.25 × 100 = 25%
  3. 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

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