Three percentage calculations, explained
X% of a number: multiply the number by the percentage divided by 100. For example, 20% of 150 = 150 × 0.20 = 30.
X is what percent of Y: divide X by Y and multiply by 100. For example, 30 out of 150 = (30 ÷ 150) × 100 = 20%.
Percentage increase or decrease: subtract the old value from the new value, divide by the old value, and multiply by 100. A rise from 150 to 180 is a 20% increase; a fall from 180 to 150 is a 16.67% decrease.
Everyday uses
Percentages appear in discounts, tips, tax, exam marks, interest, and statistics. Having a quick, reliable calculator saves mistakes when the numbers are not round.
Frequently asked questions
How do I find a percentage of a number?
Multiply the number by the percentage divided by 100. For example, 15% of 200 is 200 × 0.15 = 30.
How do I calculate percentage change?
Subtract the original value from the new value, divide by the original value, then multiply by 100.
How do I work out what percent one number is of another?
Divide the first number by the second and multiply by 100.
Can it handle decimals?
Yes, all three modes accept decimal inputs for precise results.