Percentage Difference Calculator
Calculate the percentage difference between two values, percentage change, and relative error.
Results
What is it?
Percentage Change measures how much a value changed relative to a reference (old) value: ((new ā old) / |old|) Ć 100. It is directional ā positive means an increase, negative a decrease. Percentage Difference is symmetric ā it compares two values without designating either as the reference by using their average as the denominator: |vā ā vā| / ((vā+vā)/2) Ć 100.
How to use
Enter Value 1 as the reference (baseline, old value) and Value 2 as the new or comparison value. Percentage Change uses Value 1 as the denominator; Percentage Difference uses the average of both. The Absolute Difference is simply Value 2 ā Value 1 (negative if Value 2 is smaller).
Example scenario
A stock price rose from $100 to $125. Absolute diff = +$25. Percentage Change = (125ā100)/100 Ć 100 = +25% (a 25% gain from the reference). Percentage Difference = |100ā125|/((100+125)/2) Ć 100 = 25/112.5 Ć 100 ā 22.22% (neither value is "primary").
Pro tip
Use Percentage Change in finance and business (e.g., revenue growth YoY, price change) where Value 1 is clearly the baseline. Use Percentage Difference in science and experimental contexts where neither value is the "true" reference (e.g., comparing two measurements of the same quantity). For relative error, use |measured ā true| / |true| Ć 100 ā this is percentage change where "true" plays the role of Value 1.