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Percentage Change Calculator

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.

The starting value you are comparing from.

The value it changed to.

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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