Calculate percentages instantly: find what percent of a number is, calculate percentage change, or reverse-engineer the original value from a percentage result.
“What is 15% of 240?”— multiply 0.15 × 240 = 36. “What is the percentage change from 200 to 250?” — (250 − 200) / 200 × 100 = 25% increase. “75 is 25% of what?”— 75 / 0.25 = 300. These three operations cover virtually every percentage calculation you encounter in daily life.
A 50% drop followed by a 50% gain does notreturn to the original value. If $100 drops 50% to $50, then gains 50%, you reach $75 — a net 25% loss. To recover from a 50% loss, you need a 100% gain. To recover from a 90% loss, you need a 900% gain. This asymmetry is critical in investing: the larger the drawdown, the exponentially larger the recovery needed. A stock that falls from $100 to $10 (90% loss) must rise from $10 to $100 (900% gain) just to break even.
Sales tax:A $49.99 item with 8.25% tax costs $49.99 × 1.0825 = $54.12. Discounts:A “30% off” $120 jacket is $120 × 0.70 = $84. Tips:18% of a $67 dinner bill is $67 × 0.18 = $12.06. Markup:A retailer buying at $40 wholesale and selling at $100 has a 150% markup but only a 60% profit margin — these are different calculations. Markup is relative to cost; margin is relative to selling price.
If an interest rate rises from 3% to 5%, that is a 2 percentage point increase but a 66.7% percentageincrease. The distinction matters enormously in finance and statistics. News headlines often conflate the two: “unemployment rose 2%” could mean from 5% to 7% (2 points, a 40% increase) or from 5% to 5.1% (a 2% increase, 0.1 points). Always clarify whether you mean absolute points or relative percentage change.
Use the Reverse % mode. If you paid $84 after a 30% discount, the original price was $84 / (1 − 0.30) = $84 / 0.70 = $120. This is because you paid 70% of the original. The same logic applies to calculating pre-tax prices: if the total was $54.12 with 8.25% tax, the pre-tax price was $54.12 / 1.0825 = $49.99.
Markup is calculated on the cost: (Sell − Cost) / Cost × 100. Margin is calculated on the selling price: (Sell − Cost) / Sell × 100. A product bought for $40 and sold for $100 has a 150% markup but only a 60% margin. Markup is always higher than margin for the same transaction. Retailers typically discuss markup; financial analysts prefer margin.
Yes. A negative percentage change indicates a decrease. If revenue drops from $500,000 to $350,000, the percentage change is (350,000 − 500,000) / 500,000 × 100 = −30%. The absolute value tells you the magnitude of change; the sign tells you the direction. In our calculator, negative results in % Change mode always represent a decrease from the original value.