Percentage change is the difference between the new and old values divided by the magnitude of the old value: from 50 to 75 is (75 − 50) / 50 = +50%; from 200 to 150 is −25%.
Results are computed from your inputs and rounded for display. Verify important figures independently.
Enter an old value and a new value. The calculator shows the percentage change between them and the plain absolute change. A positive result means the value went up; a negative result means it went down.
Formula & methodology
Percentage change = (new − old) ÷ |old| × 100%
Absolute change = new − old
The magnitude (absolute value) of the old value is used as the base so that a move in the same direction as the starting sign reads as a positive change. Percentage change is undefined when the old value is zero, because dividing by zero has no meaningful answer — the calculator refuses that input instead of inventing one.
Worked examples
50 → 75: change +50%, absolute +25.
200 → 150: change −25%, absolute −50.
50 → 0: change −100% (the value fell to nothing).
Limits
Percentage change compares two single numbers; it is not an annualized growth rate. To compare growth over time across different periods, use a rate that accounts for the number of periods, such as a compound annual growth rate.
Frequently asked questions
Why can't the old value be zero?
Percentage change divides by the old value. Dividing by zero is undefined, so a "percent change from zero" has no honest answer — the calculator flags it rather than showing infinity or a misleading number.
How is a change from a negative number handled?
The base uses the magnitude of the old value, so moving from −50 to −25 reads as +50% — the value increased by half of its starting size. This keeps the sign of the result aligned with the direction of the move.
