Percentage Calculator
A free online percentage calculator with 5 modes: find X% of Y, calculate percentage change, increase/decrease values, reverse percentages, and split tips. Features visual percentage bars and step-by-step formula breakdowns — all calculated instantly in your browser.
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What is a Percentage Calculator?
A percentage calculator is an online tool that performs common percentage-related math operations. It handles 5 calculation modes: finding what X% of a number is, determining what percentage one number is of another, calculating percentage change between two values, increasing or decreasing a number by a percentage, and reverse percentage (finding the whole from a part). It also includes a tip calculator for splitting bills. All calculations show step-by-step formulas so you can understand the math behind the result.
How to Use This Percentage Calculator
- Select a calculation mode from the tabs (e.g., 'What is X% of Y?')
- Enter the required values in the input fields
- View the instant result with visual percentage bar
- Check the step-by-step formula breakdown to understand the math
- Use quick percentage buttons (10%, 15%, 20%, 25%, 50%, 75%) for common calculations
Frequently Asked Questions
How do I calculate what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 25 is what % of 200? → (25 / 200) × 100 = 12.5%. Use the 'X is what % of Y?' mode for instant calculation.
How do I calculate percentage increase or decrease?
For percentage change: ((New - Old) / |Old|) × 100. For example, if a price went from $80 to $100, the increase is ((100-80)/80) × 100 = 25%. Use the '% Change' mode.
What is reverse percentage calculation?
Reverse percentage finds the original whole when you know a part and its percentage. For example, if 30 is 20% of a number, the whole is 30 / (20/100) = 150.
How do I calculate a tip?
Use the Tip Calculator mode: enter the bill amount, select a tip percentage (common: 15-20%), and optionally split between multiple people. The calculator shows the tip amount, total, and per-person cost.