Percentage Change Calculator
See how much a value has gone up or down — as a percentage and as a raw difference.
Increase or decrease
A positive result is an increase, a negative result is a decrease — the sign tells you the direction.
Original of zero
Percentage change is undefined when the original value is zero, because there is nothing to compare against.
What is percentage change?
Increase or decrease, in percent
Percentage change measures how much a value has grown or shrunk relative to where it started. It turns a raw difference into a proportion, so a rise from 100 to 125 and a rise from 1,000 to 1,250 are both recognised as the same 25% change. That makes it the standard way to compare price moves, audience growth, exam improvements, and any before-and-after figure on a common scale.
Subtract the original from the new value, divide by the size of the original, and multiply by 100.
Percentage change = (new − old) ÷ |old| × 100Dividing by the absolute value of the original keeps the sign meaningful even when the starting figure is negative: the result is positive when the value rises and negative when it falls. The absolute change — simply new minus old — is shown alongside so you can see both the proportion and the actual difference.
Suppose a subscription rises from 100 readers to 125.
Find the difference
125 − 100 = 25, the absolute change.Divide by the original
25 ÷ 100 = 0.25.Convert to percent
0.25 × 100 = a 25% increase.
The percentage tells you the direction and scale of the move: +25% is a quarter larger, −50% is a halving. Watch the asymmetry — a 50% drop followed by a 50% rise does not return to the start, because each percentage is taken from a different base. For that reason, percentage change is best read as a single before-and-after comparison rather than chained across several steps. The absolute change is the figure to quote when the raw amount matters more than the proportion, such as a €25 price rise.
The arithmetic is exact, but a few cases need care.
Zero and negative starting values
When the original value is zero, the percentage change is undefined — division by zero — so the calculator shows only the absolute change. With a negative original value, the result still follows the sign of the difference, but percentages around values that cross zero can be misleading; in those cases lean on the absolute change instead.