Percentage Increase Calculator
A percentage increase is the gap between two values divided by the magnitude of the one you started from: (new − old) ÷ |old| × 100, so 80 to 100 is 20 ÷ 80 × 100, an increase of 25%. This page opens the calculator on that question, with a From box and a To box, and it prints the division it actually used underneath the answer rather than the number alone. The direction is named in words, an increase or a decrease, beside the signed figure, and a starting value of zero is refused with the reason instead of answered, because any increase from nothing is infinite.
What is the percentage change from … to …?Pick a question and fill in both boxes
Change and difference are not the same thing. Going from 80 to 100 is a 25% increase, measured against where you started. But the percentage difference between 80 and 100 is 22.22%, because that one divides by the average of the two. Change has a direction; difference does not. Reports and spreadsheets mix these up constantly, which is why both are here as separate questions.
Margin and markup are the same profit over two different divisors. Something that costs 40 and sells for 100 earns 60 either way, but the margin divides that by the selling price and is 60%, while the markup divides it by the cost and is 150%. Margin can never pass 100%; markup has no ceiling. The profit margin question above reports both, each beside the number it divided by.
Common questions
- How do I calculate a percentage increase?
- Subtract the old value from the new one, divide by the magnitude of the old value, then multiply by 100. From 80 to 100 that is (100 − 80) ÷ 80 × 100 = 25%. This page prints the same line under the answer for whichever pair you enter, with the divisor inside absolute-value bars as ÷ |80| × 100, so the arithmetic can be checked on paper or pasted into a document rather than taken on trust. Both the rounded headline and the exact result are shown, and the Copy result button copies the exact one.
- How do I work out a percentage decrease here?
- The same two boxes do it. Put the earlier figure in From and the later one in To even when the later one is smaller: 100 to 80 comes back as -20%, and the page writes it out as a decrease of 20% as well as showing the minus sign. There is no separate decrease mode to hunt for, because it is the same division with a negative result.
- Does a 25% decrease undo a 25% increase?
- No, and this is the mistake the page is built to make visible. 80 to 100 is a 25% increase, but 100 back to 80 is a 20% decrease, because the second division is by 100 rather than by 80. A percentage change is always a share of where it started, so the two directions are not mirror images. Enter both pairs and the working line shows the two different divisors.
- Why will it not calculate an increase from zero?
- Because it is undefined. Any increase from nothing is infinite as a proportion of nothing, which is why a spreadsheet returns a divide-by-zero error on the same sum. The page says that instead of printing a number, and points at the percentage difference question, which divides by the average of the two values and can therefore express the gap between 0 and something.
- What if the starting value is negative?
- The division uses the size of the starting value rather than its sign, so going from -50 to -25 is an increase of 50%. The working line prints the absolute-value bars around the divisor, |-50| in that example, so you can see exactly which figure the result was measured against.
- Can I type a comma or a percent sign into the boxes?
- Yes. A value pasted as 1,234.5 reads as 1234.5, and a trailing percent sign is stripped, so 12% in a box is read as 12. A value that is not a number holds the headline at Ready and shows a message naming what is accepted: digits, an optional minus sign and one decimal point.
Exact, computed in double precision and cleaned to twelve significant digits, with the working shown.