Percentage Calculator: X Out of Y as a Percent

How to turn “X out of Y” into a percentage

Divide the part by the whole, then multiply by 100. For 16 out of 20: 16 ÷ 20 = 0.8, and 0.8 × 100 = 80%.

The same rule answers “14 of 25 is what percent” (56%) and “15 as a percentage of 20” (75%). The whole always goes on the bottom.

How do you calculate the percentage of a number?

Turn the percent into a decimal by dividing it by 100, then multiply. 25% of 80 is 0.25 × 80 = 20. A tip works the same way: 18% of a $45 bill is 0.18 × 45 = $8.10.

A handy shortcut: X% of Y always equals Y% of X. So 8% of 50 is the same as 50% of 8, which is 4. Flip the question whenever one side is easier to do in your head.

Common mistakes

• Dividing the whole by the part (20 ÷ 16 = 125%, not 80%).
• Forgetting to multiply by 100, which leaves 0.8 instead of 80%.
• Rounding too early on repeating decimals such as 2/3 (66.67%).

Quick answers: common scores as percentages