Percentages & change
Calculate percentages and percentage change between two values.
How to use
Choose one of four calculations: a percentage of a value, a value increased by a percentage, a value decreased by a percentage, or the percentage change from a previous value to a current one. For the first three, the result shows the amount the percentage represents and the final figure, with the calculation written out; percentage change shows the two values and the change.
The formulas are short. A percentage of a value is value × percentage ÷ 100, so 20% of 500 is 100. An increase adds that amount and a decrease subtracts it: 500 + 20% is 600 and 500 − 20% is 400. Percentage change is (current − previous) ÷ previous × 100, so going from 139 to 169 is a change of 21.58%.
A percentage change is measured against the starting value, which is why a rise and a fall of the same amount are not the same percentage. From 80 to 100 is +25%, but from 100 back to 80 is −20%. A drop is shown as a negative number. The previous value cannot be zero, because a change from nothing has no percentage; with a negative starting value, the change is measured against its size, so going from −50 to −25 counts as +50%.
Percentage change and percentage points are not the same thing, and confusing them is how a headline says one number and the data says another. A rate moving from 4% to 5% has risen by one percentage point, and by 25%.
Percentage changes are shown with two decimal places. The calculation runs in your browser; nothing is sent anywhere.
Example
20% of 500100.500 + 20% / 500 − 20%600 and 400.139 → 16921.58%. The other way, from 169 to 139, is −17.75%.4% → 5%+1 percentage point, or +25%.
Frequently asked questions
Why doesn’t adding 20% and then removing 20% get me back?
Because the second percentage is taken from a bigger number. 100 plus 20% is 120, and 20% of 120 is 24, so you land on 96. To undo an increase you divide, not subtract: 120 ÷ 1.20 = 100.
What is the difference between per cent and percentage points?
Percentage points measure the gap between two percentages; per cent measures the change relative to the starting one. From 4% to 5% is one point of difference and a 25% increase.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100: 120 out of 500 is 120 ÷ 500 × 100 = 24%. In this tool, the percentage change from 500 to 120 gives −76%, which is the same information seen from the other side: 120 is 24% of 500, so it is 76% less.
Why can’t the previous value be zero?
Because a change from zero has no percentage: any increase from nothing would be infinitely large. The tool asks for a previous value other than zero; describe that change as an amount instead.