What does this tool do?
The Percentage Change Calculator finds the percentage change between an old value and a new value. It returns the result with a sign, showing an increase as positive and a decrease as negative, and also reports the absolute difference. It is ideal for comparing changes in prices, revenue, or any numeric measurement.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
The calculation logic
Percentage change is computed with the formula (new − old) / old × 100. For example, going from 80 to 100 gives +25%, while dropping from 100 to 80 gives −20%. The tool also shows the raw difference (absolute change) between the two values.
Example uses
It is used to measure a product's price increase, an investment's return, or the change in sales between two periods. It is also handy for anyone who wants to quickly see raise rates, the effect of a discount, or growth percentages.
Frequently asked questions
Why is the result sometimes negative?
A negative result means a decrease; if the new value is smaller than the old value, the percentage change is shown with a negative sign.
What happens if the old value is zero?
When the old value is zero, the percentage change is mathematically undefined because you cannot divide by zero, so no meaningful ratio can be calculated.
Is Percentage Change Calculator free?
Yes. Percentage Change Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Percentage Change Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.