Percentage Change Calculator
How it works
The change is the new value minus the original value, and the percentage change divides that by the original value — the point everything is measured relative to. A positive result means the value grew; a negative one means it fell, and the sign is kept rather than dropped so the direction is never lost along with the size of the move.
Frequently asked questions
How is this different from this site's Percentage Calculator?
The Percentage Calculator answers "what is X% of Y" and similar single-percentage questions. This tool answers a different question: by what percent did a value change between two points — a price, a score, a measurement — which is common enough on its own to deserve its own form rather than being buried as a third option on another tool.
Why is an original value of exactly zero an error instead of showing some number?
Percentage change is measured relative to where a value started, and there is no honest way to measure a change relative to zero — the result would have to be an infinite percentage for any nonzero ending value. Rather than showing Infinity or quietly substituting a fallback number, this tool tells you plainly that the calculation is undefined in that case.
How do I read a negative result?
A negative percentage change means the value decreased, and it is shown with a minus sign rather than hidden behind an absolute value — a drop from 100 to 92 is shown as −8%, not 8%, so the direction of the change is never lost along with its size.