How to calculate percentage difference?

Percentage difference is used to compare two values when order doesn't matter (e.g., comparing the height of two buildings). Find the absolute difference between the two numbers, divide it by their average, and multiply by 100.

Formula

% Diff = (|Value A − Value B| ÷ ((Value A + Value B) ÷ 2)) × 100

Worked Example

Compare 100 and 150.

1. Difference: |100 − 150| = 50
2. Average: (100 + 150) ÷ 2 = 125
3. Calculation: 50 ÷ 125 = 0.40
4. Percent: 0.40 × 100 = 40%

Result: The percentage difference is 40%.