Percentage Calculator
Calculate any percentage: what is X% of Y, X is what percent of Y, percent increase/decrease, and more. Instant results with step-by-step explanations.
How to Use the Percentage Calculator
- Choose your calculation type (X% of Y, or X is what % of Y)
- Enter the percentage and base values
- View the result with step-by-step explanation
- Browse pre-calculated percentages below for quick reference
Pre-Calculated Percentages
Looking for a specific percentage? Browse our pre-calculated percentage pages for instant answers to common queries like "what is 15% of 200" or "what is 20% of 500". Over 600 combinations are available with step-by-step explanations.
What Is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word itself comes from the Latin "per centum," meaning "by the hundred." The percent sign (%) was standardized in the 17th century and has been a cornerstone of mathematics and commerce ever since.
Percentages make it easy to compare ratios of different magnitudes on a common scale. Whether you are calculating a 15% tip, a 30% discount, or a 7.5% annual return, the underlying math is the same: multiply the base value by the percentage divided by 100.
Despite their simplicity, percentage calculations trip people up surprisingly often — especially when dealing with successive increases and decreases, where intuition frequently misleads.
Common Uses for Percentage Calculations
Discounts and Sales Tax
Quickly determine the final price after a percentage discount or calculate the tax amount added to a purchase total.
Grade Calculations
Convert raw scores to percentages to evaluate academic performance and determine letter grades on a standardized scale.
Tip Calculation
Figure out a 15%, 18%, or 20% tip at restaurants without fumbling with mental arithmetic or pulling out a calculator.
Financial Returns and Interest
Compute investment gains, loan interest, or savings growth using percentage-based annual rates and compound formulas.
Data Analysis
Express changes in metrics as percentage increases or decreases to communicate trends clearly in reports and dashboards.
Tips for Percentage Calculations
Increase vs Decrease Formulas
Percentage increase: ((new - old) / old) x 100. Percentage decrease uses the same formula — a negative result indicates a drop.
A Common Mistake to Avoid
A 50% increase followed by a 50% decrease does not return you to the original value. 100 becomes 150, then drops to 75.
Mental Math Shortcuts
To find 15%, calculate 10% (move the decimal) and add half of that. For 25%, divide by 4. These tricks speed up everyday math.
Percentage Points vs Percentages
Going from 10% to 15% is a 5 percentage-point increase but a 50% relative increase. Confusing the two is a common communication error.