Percentage Calculator
Calculate percentages with multiple methods.
What is X% of Y?
X is what % of Y?
Percentage Change
Increase/Decrease by Percentage
📘 How It Works
Percent of a Number
To find X% of Y: multiply Y by (X/100). For example, 15% of 80 = 80 × 0.15 = 12. This is the most common percentage calculation.
What Percent X is of Y
Divide X by Y and multiply by 100: (X/Y) × 100 = percentage. For example, 24 is what % of 80? (24/80) × 100 = 30%.
Percentage Change
Calculate the difference between new and old values, divide by the old value, multiply by 100: ((new-old)/|old|) × 100. Positive = increase, negative = decrease.
Increase by Percentage
Add the percentage amount to the original: value + (value × percent/100). For example, 100 increased by 20% = 100 + 20 = 120.
Decrease by Percentage
Subtract the percentage amount from the original: value - (value × percent/100). For example, 100 decreased by 20% = 100 - 20 = 80.
💡 Common Use Cases
Sales & Discounts
Calculate sale prices. If something is 30% off, find the discount amount and final price quickly.
Tax Calculations
Add sales tax to prices. Calculate what percentage of your income goes to taxes or a specific expense.
Grade & Score Analysis
Convert points to percentages for test scores. Calculate what score you need to achieve a target percentage.
Financial Analysis
Calculate return on investment (ROI), profit margins, and year-over-year growth percentages.
Tip Calculations
Calculate gratuity at restaurants. Find 15%, 18%, 20%, or custom tip amounts on your bill.
Data Comparison
Express differences as percentages for easier understanding. How much faster, larger, or cheaper is option A vs B?