Percentage Change Calculator
Instantly calculate the percentage increase or decrease between two values. Perfect for finance, business analytics, science, and everyday math.
Calculate Percent Change
Enter your initial and final values below to instantly see the absolute difference and the relative percentage change, complete with the exact mathematical formula used.
Percentage Change Calculator
Get instant, precise calculations for growth or decline.
Understanding the Math
Key concepts behind percentage change
The Core Formula
Percentage Change = ((New Value – Old Value) / |Old Value|) × 100. The absolute value of the old value ensures the math works correctly even if the starting number is negative.
Positive vs. Negative
A positive result indicates growth or an increase. A negative result indicates a decline or decrease. A result of exactly 0% means the values are identical.
Change vs. Difference
Percentage change is directional (from A to B). Percentage difference is non-directional and uses the average of the two numbers as the denominator, not the initial value.
Real-World Applications
Used daily in finance (ROI, inflation), retail (discounts, markup), science (experimental error), and demographics (population growth rates).
Common Percentage Change Examples
A handy lookup table for everyday scenarios, helping you quickly estimate growth, discounts, or declines.
| Initial Value | Final Value | Absolute Change | Percentage Change | Common Context |
|---|---|---|---|---|
| 100 | 120 | +20 | +20.00% | Standard business growth target |
| 50 | 40 | -10 | -20.00% | Price discount or value drop |
| 200 | 250 | +50 | +25.00% | Quarterly revenue increase |
| 80 | 100 | +20 | +25.00% | Investment return (ROI) |
| 1,000 | 950 | -50 | -5.00% | Minor inventory shrinkage |
| 10 | 15 | +5 | +50.00% | Significant user base growth |
| 20 | 10 | -10 | -50.00% | Halving of a metric (e.g., headcount) |
Percentage Change FAQ
Answers to the most frequently asked questions about calculating percentages, growth rates, and mathematical formulas.
The standard formula for percentage change is: ((New Value – Old Value) / |Old Value|) × 100. This calculates the relative change as a percentage of the original starting value.
Yes. A negative percentage change simply indicates a decrease or reduction from the original value. For example, if a product’s price drops from £100 to £80, the percentage change is -20%.
Percentage change is directional; it measures the relative change from a specific initial value to a final value. Percentage difference is non-directional; it measures the absolute difference between two values relative to their average, without designating one as the “starting” point.
In Excel, if your old value is in cell A1 and your new value is in cell B1, you can calculate the percentage change by entering the formula: =(B1-A1)/ABS(A1). After pressing Enter, format the cell as a Percentage to display the result correctly.
Mathematically, you cannot calculate a percentage change if the initial value is zero, because it requires division by zero, which is undefined. In business contexts, this is often noted as “Not Applicable” (N/A) or described as an infinite increase.