Percentage Calculator
Calculate percentages, increases, decreases, differences, and reverse percentages instantly. All calculations happen in your browser with step-by-step formula breakdowns.
What is X% of Y?
X is what percent of Y?
Reverse Percentage (Find Original)
Percentage Change (Auto)
What Is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin per centum, meaning “by the hundred.” When you say 25%, you mean 25 out of every 100 — or equivalently 0.25 as a decimal. Percentages are used everywhere: discounts, tax rates, exam scores, interest rates, and statistics.
How To Calculate Percentages
To find what percentage X is of Y, use the formula (X ÷ Y) × 100. For example, 30 out of 120 is (30 ÷ 120) × 100 = 25%. To find X% of Y, use (X ÷ 100) × Y. For example, 15% of 200 is (15 ÷ 100) × 200 = 30.
Common Percentage Examples
A shop offers 20% off a $150 item. The saving is (20 ÷ 100) × 150 = $30, so you pay $120. A salary rises from $60,000 to $66,000 — that is a 10% increase. A tax of 18% on $500 adds $90, making the total $590. The reverse percentage calculator helps when you know the final price and need to find the original: $800 after a 20% discount means the original was 800 ÷ 0.80 = $1,000.