Three types of percentage problems — all answered instantly.
The Percentage Calculator answers the three most common percentage questions: What is X% of Y? X is what percentage of Y? And what is the percentage change from X to Y? Instant results for any values.
There are three slots, one per question. The first asks "what is X% of Y?" — type the percentage and the whole; the result is the part. The second asks "X is what percentage of Y?" — type the part and the whole; the result is the percentage. The third asks "from X to Y, what's the percent change?" — handy for working out a price increase, a stock move, or a weight-loss percentage. All three update live as you type. Negative results in the third slot mean a decrease; positive means an increase.
"X percent of Y" is (X ÷ 100) × Y. "X is what percent of Y" is (X ÷ Y) × 100. Percent change from old A to new B is ((B − A) ÷ A) × 100. To increase a number by P percent, multiply by (1 + P/100); to decrease, multiply by (1 − P/100). To reverse a percentage — i.e. "the price is $80 after a 20% discount, what was the original?" — divide by (1 − P/100) so $80 ÷ 0.80 = $100. Confusing the direction is the most common percentage mistake.
Working out a sale discount, calculating tax, sizing a tip, scoring an exam, comparing year-on-year revenue, working out body-weight loss, or splitting a percentage commission. The same three formulas cover most everyday questions about parts, wholes and changes.