Whether you're calculating a tip, figuring out a sale discount, analyzing growth rates, or solving math homework, percentages are everywhere. This calculator handles four common percentage problems: finding a percentage of a number, determining what percentage one number is of another, calculating percentage change between two values, and reversing a percentage to find the original number.
How to Use the Calculator
Choose from four modes:
- X% of Y: What is 15% of 200? → 30
- X is what % of Y: 30 is what % of 200? → 15%
- % Change: From 80 to 100? → +25%
- Reverse %: After 20% off, price is $80. Original? → $100
Percentage Formulas
- Percentage of value: result = (percentage / 100) × value
- What percentage: percentage = (part / whole) × 100
- Percentage change: change = ((new − old) / |old|) × 100
- Reverse percentage: original = final / (1 ± percentage/100)
Common Percentage Calculations
- Sales tax: Price × (1 + tax rate) = total
- Discounts: Price × (1 − discount rate) = sale price
- Tips: Bill × tip percentage = tip amount
- Growth rates: ((New − Old) / Old) × 100 = growth %
- Grades: (Points earned / Total points) × 100 = grade %
Step-by-Step Instructions
- 1Select the calculation mode (% of, is what %, change, or reverse).
- 2Enter the required values in the input fields.
- 3View the instant result with the formula used.
- 4See the step-by-step breakdown of the calculation.
- 5Adjust values to explore different scenarios.