Percentage Calculator
Work out percentages three ways: find X% of a number, find what percent one number is of another, or measure the percentage change between two values.
How percentage calculations work
A percentage expresses a number as a fraction of 100 — the name comes from the Latin "per centum", meaning "by the hundred". To find X% of a value, multiply the value by X and divide by 100. For example, 15% of 80 is 80 × 15 ÷ 100 = 12.
To find what percent one number is of another, divide the part by the whole and multiply by 100. Percentage change compares an old and a new value: subtract the old value from the new one, divide by the old value, then multiply by 100. A positive result is an increase, a negative one a decrease.
Percentages appear everywhere — discounts, taxes, interest rates, statistics, tips. Because they normalize values to a base of 100, they make quantities of very different sizes easy to compare.
Sources: NIST Guide to the SI — percent
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 25% of 200 is 200 × 25 ÷ 100 = 50.
How do I work out a discount price?
Calculate the discount amount (price × discount % ÷ 100) and subtract it from the original price. A $60 item at 20% off costs 60 − 12 = $48.
What is the difference between percentage change and percentage points?
Percentage change is relative to the starting value, while percentage points measure the arithmetic difference between two percentages. If a rate moves from 10% to 12%, that is a rise of 2 percentage points but a 20% relative increase.
Why is a 50% loss not recovered by a 50% gain?
Because the base changes. After a 50% loss, the remaining amount is smaller, so a 50% gain on that smaller base recovers only half of what was lost. You would need a 100% gain to get back to the start.