Percentage Calculator — Percent Change
"Percent change" measures how much a value moved between two points in time — a price increase, a salary bump, or a drop in traffic. It divides the difference between the new and original values by the original value, times 100, so a move from 120 to 150 is a 25% increase while 150 down to 120 is a 20% decrease. The sign tells you whether the value rose or fell.
Percentage calculator
Percent change
25%
Inputs used
Plain percentage arithmetic, rounded to two decimal places. Dividing by zero returns 0. An estimate for quick math, not financial or statistical advice.
Measuring movement between two values
This mode divides the difference between the new and original values by the original value, times 100, so a move from 120 to 150 is (150 − 120) ÷ 120 × 100 = 25% increase. A positive result means the value went up; a negative result means it fell.
The key detail is that change is always measured against the starting value, which is why the move is not symmetric: 120 up to 150 is a 25% increase, but 150 back down to 120 is only a 20% decrease, because the second move starts from a larger base. The original value must be non-zero — if it is zero, the tool returns 0 rather than an error.
Questions
- Why isn't a rise and the matching fall the same percent?
- Because each is measured against its own starting value. Going from 120 to 150 divides the 30-point move by 120, a 25% increase; going from 150 to 120 divides the same 30-point move by 150, a 20% decrease. The larger starting base makes the drop a smaller percentage.
- What does a negative percent change mean?
- It means the value fell. When the new number is smaller than the original, the difference is negative, so the percent change comes out below zero — a drop from 150 to 120 reads as a 20% decrease.