Four types of percentage calculation on one page — instantly solved. Find a percentage of a number, calculate percentage change, or add and subtract percentages.
Four types of percentage calculations — instantly solved.
Percentages appear everywhere — discounts, tax, interest rates, tips, test scores, and statistics. Understanding which type of calculation to use is the key skill. This calculator handles all four types instantly, updating as you type.
A percentage is just a way of expressing a number as a part of one hundred. Per cent literally means "per hundred", so 25% is another way of writing 25 out of 100, or the fraction 25/100, or the decimal 0.25. Percentages make it easy to compare quantities of different sizes on a common scale, which is why they appear everywhere from discounts and tips to interest rates and statistics.
This calculator handles the three questions people ask most. First, finding a percentage of a number — for example 15% of 200 — by converting the percentage to a decimal and multiplying. Second, working out what percentage one number is of another, by dividing the part by the whole and multiplying by 100. Third, calculating percentage change between two values, which shows how much something has grown or shrunk in relative terms.
A common source of confusion is the difference between a percentage change and a percentage point. If an interest rate rises from 4% to 5%, that is an increase of one percentage point, but a 25% increase in relative terms. Mixing the two up can make a change sound much larger or smaller than it really is. Percentage change is always calculated relative to the starting value, so the same absolute change produces a bigger percentage when the starting number is small.
Say an $80 jacket is marked down by 25%. Convert 25% to 0.25, multiply by 80 to get a $20 saving, so you pay $60. Later the price rises from $60 back to $80 — that is a $20 increase on $60, or a 33% rise, not 25%. The same $20 is a smaller share of the larger number and a larger share of the smaller one, which is exactly why percentage increases and decreases do not cancel out.
How do I find a percentage of a number?
Convert the percentage to a decimal (divide by 100) and multiply by the number. For example, 20% of 80 is 0.20 × 80 = 16.
What is percentage change?
It measures how much a value has increased or decreased relative to its original size: (new minus old) divided by old, times 100. A rise from 50 to 75 is a 50% increase.
What is the difference between percent and percentage points?
A percentage point is the plain difference between two percentages. Percent, or percentage change, expresses that difference relative to the starting value, so the two numbers are usually different.