How to calculate percentage decrease?

To calculate percentage decrease, find the difference between the starting value and the lower final value. Divide this difference by the starting value and multiply by 100. This formula is commonly used for price drops, weight loss, or traffic decline.

Formula

Decrease % = ((Start Value − End Value) ÷ Start Value) × 100

Worked Example

Stock drops from $50 to $40.

1. Loss: $50 − $40 = $10
2. Proportion: $10 ÷ $50 = 0.20
3. Percent: 0.20 × 100 = 20%

Result: It decreased by 20%.