About the Percentage Calculator
The three questions people ask about percentages are all answered here at once: what is X% of Y, what percentage is X of Y, and what is the percentage change from X to Y. Enter the first number in the pane and the second in the toolbar, and the tool shows all three results, so you do not have to remember which formula to use.
It covers everyday needs: a discount, a tip, a tax amount, a growth rate, a test score as a percentage. For writing numbers out or formatting them, the Number Formatter and Number to Words tools help.
The three formulas answer different questions and are worth keeping straight. X percent of Y is X divided by 100, times Y, so 15 percent of 250 is 37.5. X as a percentage of Y is X divided by Y, times 100, so 15 out of 250 is 6 percent. Percentage change from X to Y is Y minus X, divided by X, times 100, so 200 to 250 is a 25 percent increase. Only the change formula cares which number came first.
Two traps catch people out. Percentage changes do not cancel, so a price cut by 20 percent and then raised by 20 percent finishes 4 percent below where it started, because the second move applies to the smaller base. And a shift from 4 percent to 6 percent is a rise of two percentage points but of 50 percent, a distinction that matters in interest rates and conversion reports. For a ratio written as a fraction, Fraction to Decimal gives the decimal to multiply by 100.
How to use
- Enter the first number in the pane.
- Enter the second number in the toolbar.
- Read all three percentage results.
Common questions
- How do I find 15% of 250?
- Enter 15 as the first number and 250 as the second; the first result line shows 37.5.
- How is percentage change calculated?
- As (new minus old) divided by old, times 100. From 200 to 250 is a 25% increase.
- What if the base is zero?
- Percentage of a zero base is undefined, shown as infinity, since you cannot divide by zero.