Calculate percentages quickly and accurately with 5 calculation modes: percentage of a number, percentage change, reverse percentage, "what percent?", and tip/discount calculator with bill splitting.
Calculate what percentage one number is of another
Find % increase or decrease between two values
Find the original value from a known percentage
Add or subtract a percentage from any number
Convert any ratio or fraction to a percentage
6 different percentage calculation modes in one tool
Select from: % of number, % change, % difference, or add/subtract %.
Input the numbers for your specific percentage calculation.
The answer appears immediately with the formula shown.
Read the step-by-step formula explanation to understand how it works.
| Type | Formula | Example |
|---|---|---|
| X% of Y | (X / 100) × Y | 15% of 200 = 30 |
| % Change | ((New − Old) / |Old|) × 100 | (125−100)/100 × 100 = +25% |
| What % is X of Y? | (X / Y) × 100 | 30/200 × 100 = 15% |
| Reverse (after discount) | Value / (1 − %/100) | 85 / 0.85 = 100 (original) |
| Reverse (after increase) | Value / (1 + %/100) | 115 / 1.15 = 100 (original) |
Formula: (X / 100) × Y. For 15% of 200: (15/100) × 200 = 30. Think of it as: 1% of 200 is 2 (200 ÷ 100), so 15% is 2 × 15 = 30. Use the "% of Number" tab for instant calculation.
Formula: ((New − Old) / |Old|) × 100. Price from $100 to $125: ((125−100)/100) × 100 = +25% increase. Price from $100 to $80: ((80−100)/100) × 100 = −20% decrease. Positive = increase, negative = decrease.
Formula: (X / Y) × 100. Got 45 out of 60 on a test: (45/60) × 100 = 75%. Sold 250 out of 1,000 products: (250/1000) × 100 = 25% market share. Use the "What %?" tab for instant answers.
Use the reverse percentage formula. Item costs $85 after a 15% discount: $85 / (1 − 0.15) = $85 / 0.85 = $100 original price. Item costs $115 after a 15% markup: $115 / (1 + 0.15) = $115 / 1.15 = $100 original price. Use the "Reverse %" tab.
For a 15% tip on $85: ($85 × 0.15) = $12.75 tip; total = $97.75. For a 20% discount on $120: ($120 × 0.20) = $24 discount; final price = $96. The Tip/Discount tab also handles bill splitting between multiple people and works for taxes too.
Choose your calculation type: "What is X% of Y?", "X is what % of Y?", "Percentage change from X to Y", or "X increased/decreased by Y%". Enter your values and click Calculate. Results show the answer plus step-by-step working so you understand the math.
Percentage calculations are used in virtually every aspect of business and daily life: discounts, tax rates, tips, profit margins, investment returns, grade calculations, and statistical analysis. Knowing how to calculate percentages accurately prevents costly errors in pricing, budgeting, and financial reporting.
10% tip on $85 = $8.50. 20% discount on $150 = $30 off, $120 final. 15% VAT on £200 = £30 tax, £230 total. 7% sales tax on $99 = $6.93. 5% annual raise on $60,000 = $3,000 increase. 25% profit margin on $80 cost = $26.67 profit, $106.67 price. Percentage change: From 200 to 250 = 25% increase.
Percentage calculations appear constantly in financial decisions, business analysis, and daily life. Here are worked examples for the most common scenarios:
Tipping at a restaurant: Your bill is $47.50. For 20%: move the decimal left one place to get 10% ($4.75), then double it: $9.50. Total: $57.00. For 15%: take 10% ($4.75) and add half of that ($2.38): tip = $7.13. These mental shortcuts give fast estimates; this calculator gives the exact amount when splitting a group bill.
Discount and sale prices: A $120 jacket is "30% off." Discount = $120 × 0.30 = $36. Sale price = $120 − $36 = $84. Alternatively: $120 × (1 − 0.30) = $120 × 0.70 = $84. The shortcut "multiply by the remaining percentage" calculates the final price directly. Watch for retailers who inflate "original prices" before applying a discount — compare the discounted price against current market value, not the stated pre-discount price.
Percentage change (growth/decline): Website traffic went from 4,200 visits in January to 6,100 in February. Percentage change = ((6,100 − 4,200) ÷ 4,200) × 100 = +45.2% growth. The same formula applies to revenue growth, weight change, investment returns, or any metric tracked over time — and critically, it can produce negative values for declines.
Income and rent affordability: Rent = $1,450/month, take-home pay = $3,800/month. Rent as a percentage of income = (1,450 ÷ 3,800) × 100 = 38.2%. Financial advisors recommend keeping housing costs under 28–30% of gross income; this calculation against take-home (net) income gives a more accurate picture of real affordability pressure.