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Enter the old and new value to see the percentage change and the raw difference.
Percentage change measures how much a value has grown or shrunk relative to where it started. A $10 rise means very different things on a $20 item and a $2,000 item, and expressing it as a percentage puts both on the same scale. That makes it the standard way to compare price rises, salary changes, population growth, website traffic, test scores and investment returns.
A positive result is an increase and a negative result is a decrease. The calculator also shows the raw difference, so you see both the absolute change and the relative one.
% change = (new − old) ÷ |old| × 100
The old value is always the base. Dividing by its absolute value keeps the sign meaningful when the starting number is negative, such as a loss that shrinks, or a temperature that moves from −10° to −5°.
A product's price goes from 80 to 100:
Now reverse it: 100 back down to 80 is a difference of −20, and −20 ÷ 100 = −20%. The same 20-unit move is 25% one way but only 20% the other, because the base changes. That asymmetry is why a 50% fall needs a 100% rise to recover.
If an interest rate moves from 4% to 5%, it rose by 1 percentage point but by 25 percent (1 ÷ 4). News reports often mix the two up. Use percentage points for the gap between two percentages, and percent change for the relative movement.
The formula divides by the old value, and dividing by zero is undefined. Going from 0 to anything is an infinite percentage increase, so quote the raw difference instead.
No. Percentage change has a direction (old → new) and uses the old value as the base. Percentage difference compares two values with neither as the starting point, and divides by their average, so the answer is the same whichever order you enter them.
Multiply the old value by (1 + change ÷ 100). For example, 80 increased by 25% is 80 × 1.25 = 100, and 80 decreased by 25% is 80 × 0.75 = 60.