Percentage Change Calculator
Find the percentage change between two numbers, with the direction, the absolute difference and the working shown step by step.
How to use it
- Put the earlier number in the first box and the later one in the second.
- A positive result is an increase, a negative one is a decrease.
- The working underneath shows the substitution so you can check it by hand.
Examples
| 80 → 100 | +25% |
| 100 → 80 | −20% |
| 50 → 50 | 0% |
Percentage change measures a move relative to where it started, which is why the same journey looks different in each direction. Going from 80 to 100 is a +25% change, because the comparison base is 80. Coming back down from 100 to 80 is only −20%, because now the base is 100. The absolute gap — 20 — never changed; only the base did.
That asymmetry trips people up constantly in real decisions: a stock that drops 50% needs to rise 100%, not 50%, to get back to where it started.
Worked example
A shop's weekly takings go from £4,200 to £4,830. The change is (4,830 − 4,200) ÷ 4,200 × 100 = +15%. If takings had instead fallen from £4,830 to £4,200, the change would be (4,200 − 4,830) ÷ 4,830 × 100 = −13.04%, not −15% — the same swing, a different percentage, because the base flipped.
Questions people ask
Why is 80 → 100 a 25% rise but 100 → 80 a 20% fall?
Because the percentage is always measured against the starting value. Going up, the base is 80; coming down, the base is 100. The same absolute change gives different percentages.
What is the difference between percentage change and percentage points?
Percentage change is relative — 4% to 5% is a 25% increase. Percentage points are absolute — the same move is +1 percentage point.
Is anything sent to a server?
No. Every calculation runs in your browser, so nothing you type is uploaded and the page keeps working offline once it has loaded.
Last updated 17 August 2026