How to use
- Choose the question that matches your calculation.
- Enter the two numbers in the order shown.
- Select "Calculate" to see the answer and formula.
Five percentage formulas
- Percentage of a number: percentage × number ÷ 100.
- One number as a percentage of another: first number ÷ second number × 100.
- Percentage change: (new value − original value) ÷ original value × 100.
- Percent off: original price × (1 − discount ÷ 100).
- Percentage difference (a common symmetric definition): |first number − second number| ÷ ((first number + second number) ÷ 2) × 100.
For example, 15% of 200 is 30. A change from 80 to 100 is a 25% increase. Taking 20% off 50 leaves 40. The percentage difference between 80 and 100 is 22.22%.
Change or difference?
Percentage change uses the original value as its base, so order matters. Percentage difference uses the average of the two numbers and gives the same answer in either order.
Limitations
Negative inputs are not supported. Use percentage change to measure a decrease. You can't divide by a zero base or work out a percentage change from zero, and this tool can't calculate the percentage difference between 0 and 0. Discounts must be between 0% and 100%.
Frequently asked questions
Why is my percentage change negative?
A negative result means the new value is lower than the original value. For example, going from 100 to 80 is a 20% decrease.
What is the difference between percent and percentage points?
Going from 4% to 5% is a rise of 1 percentage point. Relative to the original 4%, that is a 25% increase.
Can I use negative numbers?
No. Enter zero or positive numbers. A result can still be negative: going from 100 to 80 is a change of -20%.
Does a 10% rise followed by a 10% fall cancel out?
No. Starting at 100, a 10% rise gives 110. A 10% fall from 110 gives 99, because the second percentage uses a different base.