FreeToolStation

Percentage Change Calculator

The percentage increase or decrease between two numbers.

Math Calculators Free, no sign-up Runs in your browser
—
Percentage change
—
Absolute change
—
Direction
—
Going back would be
—
New as a share of old
MeasureValue
An increase and the decrease that undoes it are not the same percentage. Up 25% then down 25% does not return you to where you started, and the "going back" figure is the one that actually would.

About the Percentage Change Calculator

Percentage Change Calculator works out the percentage increase or decrease between two numbers and shows the arithmetic: the difference divided by the original value, times a hundred. The original value is the base, and getting that the wrong way round is the single most common mistake with percentages.

The reverse figure is here because of that. Going from 80 to 100 is a 25 per cent increase; going from 100 back to 80 is a 20 per cent decrease. The same twenty units, two different percentages, because the base changed. This is why a shop can cut a price by 30 per cent and then raise it by 30 per cent and end up below where it started, and why a stock that falls 50 per cent needs to double to recover.

Change from zero is reported as undefined rather than as infinity. There is no percentage of nothing that produces something, so the calculator gives the absolute change and says why the percentage cannot exist.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

Looking for something this does not cover? FreeToolStation.com is a second collection of the same kind of everyday tools, and it is worth a look if percentage change calculator is only part of what you are working on.

How to use the Percentage Change Calculator

  1. Enter from (the original value) and to (the new value)Decimals are fine, and thousands separators are accepted and ignored.
  2. Read the percentage change, absolute change and directionThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
  3. Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row and read the formula with your own numbers in it.

Features

  • Shows percentage change, absolute change, direction, going back would be and new as a share of old together, so you are not running it twice
  • A results table you can read across
  • Prints the formula with your own figures substituted in
  • Updates as you type, with no button to press and no page reload
  • Copy the result in one click
  • Free, no sign-up, and it runs entirely in your browser

Who uses this tool

The percentage change calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Working out revenue growth between two periods
  • Checking a price rise or a discount claim
  • Reporting a change in a metric month on month
  • Finding what reduction undoes a given increase

Frequently asked questions

Which number is the base?

The original one, always. The difference is divided by where you started, not by where you ended up, which is why the increase and the matching decrease are different percentages.

What about negative numbers?

The difference is divided by the absolute value of the original, so a move from -50 to -25 is reported as a 50% increase. That is the usual convention, but percentage change across zero is best described in absolute terms.

Is this the same as percentage difference?

No. Percentage change has a direction and a starting point. Percentage difference compares two values with no sense of which came first, and divides by their average instead.

If the percentage change calculator is not quite what you need, these other free tools solve closely related problems, and there are 25 more in math calculators.

Percentage Calculator

Three calculators: percent of a number, what percent one number is, and change.

Math Calculators Use tool

Discount Calculator

Enter a price and a discount to get the saving, the final price and tax.

Business Calculators Use tool

Markup Calculator

Markup, margin and selling price, and the difference between the first two.

Business Calculators Use tool

Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.