The 6 most common percentage calculations
Percentages show up everywhere — discounts, tax, tips, statistics, finance, growth rates. This tool handles the six most common scenarios so you never have to Google "how to calculate X% of Y" again.
1. What is X% of Y?
Result = Y × X / 100. Example: 15% of 200 = 30.
2. Percent change (from X to Y)
% Change = (Y − X) ÷ X × 100. A positive number means increase; negative means decrease. Example: from 80 to 100 = +25%.
3. X increased by Y%
Result = X × (1 + Y / 100). Example: 200 increased by 10% = 220.
4. X decreased by Y%
Result = X × (1 − Y / 100). Example: 200 decreased by 10% = 180.
5. Markup (cost → price)
Price = Cost × (1 + Markup% / 100). A $50 item with 40% markup sells for $70.
6. Margin (cost + margin% → price)
Price = Cost ÷ (1 − Margin% / 100). If you want 25% margin on a $30 cost, you need to sell at $40 (your profit is $10, which is 25% of $40).
Markup vs margin — easy to confuse!
A $10 product sold for $15 has 50% markup (added $5 to cost) but only 33% margin ($5 profit ÷ $15 price). Both are common, but they measure different things.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply by the percentage as a decimal. 25% of 200 = 0.25 × 200 = 50.
How do I calculate percent change?
(New − Old) ÷ Old × 100. From 100 to 120 = +20%.
Markup vs margin?
Markup = profit ÷ cost. Margin = profit ÷ price. A $15 item with $5 profit has 50% markup and 33% margin.