ToolFactory

Percentage Change Calculator

Percentage Change Calculator: free, instant and private. The base is always the old value, so a rise and a following fall of the same percent do not cancel out.

How the Percentage Change Calculator works

The Percentage Change Calculator takes From value, To value and returns the answer instantly — no button to hunt for, no page reload. The base is always the old value, so a rise and a following fall of the same percent do not cancel out. A 50% gain needs only a 33.3% loss to be wiped out.

Enter your own numbers to replace the example values; the result panel updates as you type. Everything runs in this single page, so nothing you enter leaves your device.

Formula used

change % = ((new − old) ÷ old) × 100

SymbolMeaning
oldthe starting value
newthe value after the change

The base is always the old value, so a rise and a following fall of the same percent do not cancel out. A 50% gain needs only a 33.3% loss to be wiped out.

Inputs used: From value, To value.

Worked example

Take the default example — from value of 250, to value of 300:

Frequently asked questions

What formula does the Percentage Change Calculator use?
It uses change % = ((new − old) ÷ old) × 100, where old is the the starting value; new is the the value after the change.
Is the Percentage Change Calculator free?
Yes. There is no signup, no usage limit and no watermark — the calculator runs entirely in your browser.
How do I read the result?
The base is always the old value, so a rise and a following fall of the same percent do not cancel out. A 50% gain needs only a 33.3% loss to be wiped out.
Does the Percentage Change Calculator store or send my data?
No. Every calculation happens locally in the page, so the numbers you type are never uploaded or logged.
Does it work on a phone and offline?
Yes — the page is a single lightweight file that adapts to any screen size. Once it has loaded it keeps working without a network connection.