Percentage Change

The Percentage Change tool measures how much a value has increased or decreased relative to its starting point, expressing the difference as a percentage. It answers questions like how much a price rose, how much traffic grew, or how much a metric fell, giving a normalized figure that is comparable across values of very different sizes.

The calculation takes the new value minus the original value, divides that difference by the original value, and multiplies by 100. A positive result indicates a percent increase and a negative result a percent decrease. The original value serves as the denominator, which is why the same absolute change can produce very different percentages depending on the starting point.

This is widely used in finance to track returns and price movements, in analytics to report growth or churn, and in everyday comparisons such as salary raises or price hikes. It complements a general percentage calculator for simpler proportion math and works well alongside discount or markup tools when reasoning about pricing.

Watch for the asymmetry between increases and decreases: a 50 percent drop followed by a 50 percent rise does not return you to the start, because the second percentage is taken on a smaller base. Also note that percentage change is undefined when the original value is zero, since you cannot divide by zero, so the tool needs a nonzero starting figure.