Result
20% of 100 is 20
HOW IT WORKS
This percentage calculator helps you solve common percentage problems instantly. Choose your calculation type (what is X% of Y, what % is X of Y, or increase/decrease), enter your numbers, and get the result immediately with a clear formula explanation.
COMMON PERCENTAGE CALCULATIONS
Sales Tax: Most US states charge 4-10% sales tax. Multiply price by tax rate to get tax amount. Example: $100 item with 8% tax = $100 × 0.08 = $8 tax.
Discounts: A 20% discount on $100 means you pay $80. Calculate: $100 - ($100 × 0.20) = $80.
Tips: Restaurant tip is typically 15-20% of pre-tax bill amount.
Interest Rates: Credit cards charge 15-25% APR. A $1,000 balance at 20% APR costs $200/year in interest if unpaid.
Salary Increases: A 5% raise on $50,000 salary = $50,000 × 0.05 = $2,500 increase = $52,500 new salary.
PERCENTAGE FORMULAS EXPLAINED
What is X% of Y? Multiply Y by (X/100). Example: What is 15% of 80? = 80 × 0.15 = 12.
X is what % of Y? Divide X by Y, multiply by 100. Example: 20 is what % of 80? = (20/80) × 100 = 25%.
Percentage Increase: ((New - Old) / Old) × 100. Example: Price goes from $50 to $60 = ((60-50)/50) × 100 = 20% increase.
Percentage Decrease: ((Old - New) / Old) × 100. Example: Price drops from $100 to $80 = ((100-80)/100) × 100 = 20% decrease.
Reverse Calculation: If price after 20% increase is $60, original price = $60 / 1.20 = $50.
REAL-WORLD APPLICATIONS
Percentages are everywhere: calculating test scores (18/20 = 90%), comparing products (which offers a better discount?), understanding nutrition labels (20% daily value), analyzing data (conversion rates, growth rates), budgeting (30% of income on housing), and financial planning (compound interest, investment returns).
Understanding percentages helps you make better financial decisions, compare deals effectively, and interpret statistics correctly in news and research.