Percentage Calculator

Percentages are one of the most practically useful areas of everyday math — appearing in sales tax, discounts, tips, investment returns, grade calculations, salary raises, and virtually every numeric comparison you make. Yet many people struggle with quick percentage calculations.

This calculator solves all three types of percentage problems: (1) "What is X% of Y?" — useful for calculating tips, discounts, and portions; (2) "X is what percent of Y?" — useful for converting scores to percentages and comparing quantities; and (3) "What is the percent change from X to Y?" — useful for tracking price changes, salary increases, and performance metrics.

Understanding the difference between percentage and percentage points is critical, especially when reading news and financial reports. If a savings rate rises from 10% to 12%, that's a 2 percentage point increase but a 20% relative increase. Politicians and media outlets often deliberately conflate the two. "Interest rates went up 25%" sounds alarming; "interest rates went up 0.25 percentage points" (from 5% to 5.25%) sounds ordinary. Same fact, different framing.

Compound percentage changes don't add up the way you might expect. If a stock goes up 50% and then down 33%, it's back to where it started — not up 17%. If prices rise 10% and then rise another 10%, the total increase is 21% (not 20%) because the second 10% is applied to the already-inflated price.

To calculate percentages mentally: For 10%, move the decimal left one place. For 5%, halve the 10% figure. For 20%, double the 10% figure. For 25%, divide by 4. For 1%, move the decimal two places left. These building blocks handle most real-world situations without a calculator.