A versatile percentage calculator with multiple calculation modes. Find X% of Y, calculate percentage change, add or subtract percentages, and calculate tips with instant results and visual indicators.
30
15% of 200 = 30
$15.3
$100.3
18%
Choose from four calculation modes using the tabs. Mode 1 'What is X% of Y?' - enter a percentage and a number to find the result (e.g., 15% of 200 = 30). Mode 2 'X is what % of Y?' - enter two numbers to find the percentage relationship (e.g., 30 is 15% of 200). Mode 3 'Percentage Change' - enter an original value and a new value to calculate the percentage increase or decrease (e.g., 100 to 150 = +50%). Mode 4 'Add/Subtract %' - add or subtract a percentage from a number (e.g., 200 + 15% = 230). Each mode shows a visual percentage bar and the result in large text. The bonus tip calculator section lets you calculate the tip amount and total bill from a bill amount and tip percentage.
Percentage calculations are used everywhere in daily life and professional contexts: calculating discounts during shopping (30% off $59.99), figuring out tax amounts, determining tip amounts at restaurants, analyzing financial data like profit margins and growth rates, academic grading (85 out of 100 = 85%), real estate commission calculations, investment return percentages, cooking recipe scaling, fitness tracking (percentage of daily goals), project progress tracking (350 of 1000 tasks = 35% complete), A/B test conversion rate comparisons, and salary increase or decrease calculations.
Percentage calculations use these standard formulas: 'X% of Y' = (X/100) × Y. 'X is what % of Y' = (X/Y) × 100. 'Percentage change' = ((new - old) / |old|) × 100, where a positive result indicates an increase and a negative result indicates a decrease. 'Add X% to Y' = Y × (1 + X/100). 'Subtract X% from Y' = Y × (1 - X/100). All calculations use JavaScript's native floating-point arithmetic (IEEE 754 double precision). Results are displayed with appropriate precision - whole numbers for clean results, up to 4 decimal places for fractional results. The visual percentage bar uses CSS width transitions for smooth animation.
Use the formula: ((new value - old value) / old value) × 100. For example, if a price went from $80 to $100: ((100 - 80) / 80) × 100 = 25% increase. Use the 'Percentage Change' mode in this calculator for instant results.
Multiply the number by the percentage divided by 100. For example, 15% of 200 = 200 × (15/100) = 200 × 0.15 = 30. Use the 'What is X% of Y?' mode in this calculator.
A common tip is 15-20% of the pre-tax bill. For a $50 bill: 15% tip = $50 × 0.15 = $7.50, 20% tip = $50 × 0.20 = $10.00. Use the tip calculator section in this tool for quick calculations including the total amount.
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