How this calculator works
A percentage is a fraction out of 100. Use the first option to find a share of a number, such as a 15% tip or 30% discount; the second to see how large one value is compared with another; and the last three for markups, discounts and growth rates.
Formula
X% of Y = X ÷ 100 × Y. Percent change = (new − old) ÷ |old| × 100.
Frequently asked questions
What if the old value is negative?
This calculator divides by the absolute value of the starting number, so the sign of the result shows the direction of the change.
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 0.15 × 200 = 30.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value and multiply by 100. A negative result is a decrease.
How do I take a discount off a price?
Use "Decrease Y by X%". A 20% discount on $250 gives $200.