Percentage Calculator
Find a percentage of a number, or the percentage change between two numbers.
Preparing the calculator…
How it works
This calculator answers the three most common percentage questions: what a percentage of a number is, what percentage one number is of another, and by what percentage a value has changed.
X% of a number is the number × X ÷ 100. To find what percentage a part is of a whole, divide the part by the whole and multiply by 100.
A percentage change compares the new value with the starting value: (new − old) ÷ |old| × 100, where |old| is the size of the starting value, ignoring its sign. A positive result is an increase and a negative result is a decrease. Because the change is measured against the size of the starting value, it also works for negative numbers.
Calculations are exact; only the final result is rounded, to 4 decimal places. A whole, or a starting value, of zero has no percentage answer, so the calculator shows an error instead of a misleading number.
Worked examples
A 15% discount on 240 AED
Discount = 240 × 15 ÷ 100 = 36 AED, so the discounted price is 240 − 36 = 204 AED.
45 correct answers out of 60
45 ÷ 60 × 100 = 75%.
A price falls from 125 to 100
(100 − 125) ÷ 125 × 100 = −20%, a decrease of 20%.
The price rises back from 100 to 125
(125 − 100) ÷ 100 × 100 = 25%. Returning to the same price needs a 25% rise, not 20%, because the change is measured from a smaller starting value.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 240 is 240 × 15 ÷ 100 = 36.
Why doesn't a 20% rise undo a 20% fall?
Each change is measured from its own starting value. A fall from 125 to 100 is −20%, but the rise from 100 back to 125 is +25%.
What is the difference between a percentage change and a percentage-point change?
If a rate moves from 5% to 6%, it has risen by 1 percentage point, but by 20% in relative terms (1 ÷ 5 × 100). This calculator's percentage change gives the relative change.
Can I use negative numbers?
Yes. A change is measured against the size of the starting value, so a move from −50 to −25 is a 50% increase.
Why can't I calculate a change from zero?
Percentage change divides the difference by the absolute value of the starting value. When the starting value is zero, the calculation is undefined, so the calculator shows an error.
How precise are the results?
The calculation is exact, with no floating-point errors, and the result is rounded to 4 decimal places. For example, 1 out of 3 is shown as 33.3333%.
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