Percentage Calculator

Percentage Calculator FAQs

How do I calculate a percentage of a number?

Convert the percentage to a decimal and multiply. 15% of 240 is 0.15 × 240 = 36. To do it mentally, find 10% first by moving the decimal point one place left (24), then take half of that for 5% (12) and add: 24 + 12 = 36. This decompose-into-tens-and-fives method handles most everyday percentages without a calculator.

What is the difference between percentage change and percentage points?

Percentage points describe an absolute difference between two percentages, while percentage change describes a relative one. Going from 4% to 6% is a rise of 2 percentage points, but it is a 50% increase, because 2 is half of 4. News reporting mixes these up constantly, and the difference matters most for interest rates, polling and fees.

How do I work out a percentage increase or decrease?

Divide the difference by the original value and multiply by 100. Going from 80 to 100: the difference is 20, and 20 ÷ 80 × 100 = 25% increase. Going from 100 to 80: 20 ÷ 100 × 100 = 20% decrease. The same absolute change gives different percentages because the base differs, which is why percentage declines never symmetrically undo increases.

How do I calculate a discount price?

Multiply the original price by (1 minus the discount rate). 30% off $85 is 85 × 0.7 = $59.50. For stacked discounts, multiply the multipliers rather than adding the percentages: 30% off then a further 20% off is 0.7 × 0.8 = 0.56, which is 44% off, not 50%. This is the most common retail pricing mistake.

How do I find what percentage one number is of another?

Divide the part by the whole and multiply by 100. If 18 of 45 students passed, then 18 ÷ 45 × 100 = 40%. To check the answer, reverse it: 40% of 45 is 0.4 × 45 = 18. If the part is larger than the whole, the result exceeds 100%, which is valid and usually means the two numbers are not a part-and-whole pair.