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Percentage Change Calculator

See the percentage increase or decrease between two values, plus the absolute difference.

The starting value you are comparing from.

The value it changed to.

About this tool

Percentage change measures how much a value has grown or shrunk relative to where it started. It is the standard way to compare movements of very different sizes — a $2 rise matters far more on a $10 item than on a $1,000 one, and percentage change captures exactly that.

How to use it: enter the original value and the new value, then press Calculate. You get the percentage change, whether it is an increase, decrease or no change, and the absolute difference between the two numbers.

The formula is: change % = ((new − original) ÷ |original|) × 100. A result of 25 means the value grew by a quarter of its starting point; −20 means it lost a fifth. Because the formula divides by the original value, a starting value of zero has no defined percentage change — the calculator tells you this clearly instead of returning a meaningless number.

How to calculate percentage change

  1. Subtract the original value from the new value: new − original.
  2. Divide the result by the original value.
  3. Multiply by 100 to get a percentage. A positive result is an increase, a negative result a decrease.

Example: a price goes from 80 to 100. The difference is 20, and 20 ÷ 80 = 0.25, so the price rose by 25%.

Worked examples

OriginalNewDifferencePercentage change
80100+20+25%
10080−20−20%
5075+25+50%
200150−50−25%
40100+60+150%
1.201.50+0.30+25%

Why a rise and a fall of the same percentage don’t cancel out

Each percentage is measured from a different starting point. If a price rises 25% from 100 to 125, a 25% cut takes it to 93.75, not back to 100 — to get back you only need a 20% cut, because 25 is 20% of 125.

The same is true for losses: after a 50% fall, you need a 100% rise to get back to where you started.

Percentage change vs percentage points

When the values are themselves percentages, say which you mean. If an interest rate goes from 2% to 3%, it has risen by 1 percentage point — but by 50% in relative terms (1 ÷ 2 = 0.5). News reports and contracts usually use percentage points for rates.

Finding the original value

If you know the new value and the percentage change, divide the new value by (1 + change ÷ 100). A price of 120 after a 20% increase was 120 ÷ 1.20 = 100. A price of 60 after a 25% discount was 60 ÷ 0.75 = 80.

Frequently asked questions

Subtract the original value from the new value, divide by the original value, and multiply by 100. Going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.

Because the base changes. 80 increased by 25% is 100, but 100 decreased by 25% is 75, not 80. Each percentage is measured against its own starting value — going back from 100 to 80 is only a 20% decrease.

Percentage change from zero is mathematically undefined, since the formula divides by the original value. The calculator shows a clear explanation instead of Infinity, and suggests using the absolute difference instead.

Yes — whenever a value more than doubles. Going from 50 to 125 is a 150% increase. Decreases, however, are capped at 100%, which means the value fell to zero.

The absolute difference is the plain gap between the two numbers (100 − 80 = 20). Percentage change expresses that gap relative to the starting value (25%). This calculator shows both.

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