What is X% of Y?
X is what % of Y?
About Percentage Calculator
Percentage calculations are fundamental in everyday life and professional work. Whether you are figuring out a tip at a restaurant, calculating sales tax, determining what fraction of a budget has been spent, or comparing growth rates, percentages simplify the comparison of proportions. This calculator supports two modes: finding a percentage of a number (e.g. 15% of 200 = 30) and determining what percentage one number represents of another (e.g. 30 is 15% of 200). Both modes deliver instant, accurate results right in your browser.
How to Use Percentage Calculator
- Choose your calculation mode: "What is X% of Y?" or "X is what % of Y?"
- Enter the values in the corresponding fields (percentage and whole, or part and whole).
- The result updates automatically. Click Clear all to reset for a new calculation.
Key Features
- Two calculation modes covering the most common percentage questions
- Real-time results that update as you type — no submit button needed
- Clean, minimal interface focused on speed and usability
- Handles decimals and large numbers accurately
- Entirely browser-based with no data sent to any server
When to Use This Tool
- Calculating discounts, tips, or sales tax amounts
- Determining what percentage one value is of another (e.g. budget spent vs. total)
- Quick math for school homework, business reports, or financial analysis
- Verifying percentage calculations in spreadsheets or documents
Technical Details
Mode A computes (X / 100) × Y. Mode B computes (X / Y) × 100. Division by zero (Y = 0 in Mode B) is caught and an error message is displayed. JavaScript floating-point arithmetic is used, which provides precision sufficient for virtually all practical percentage calculations. For more advanced math utilities, explore the Fraction Calculator.
Conclusion
Whether you need a quick discount calculation or want to know what fraction of a total a number represents, this free Percentage Calculator delivers instant, accurate results. It runs in your browser with no installation, no sign-up, and complete privacy.