How to Calculate Percentage Decrease

Just as percentage increase tracks growth, percentage decrease quantifies reduction. When retail stores mark down inventory, fuel prices fall, or utility bills decline after energy-saving renovations, percentage decrease measures the magnitude of that decline relative to the starting point.

The Percentage Decrease Formula

The formula for percentage reduction is:

Percentage Decrease = ((Original Value - New Value) ÷ Original Value) × 100

Because the original value is greater than the new value, subtracting the new value yields a positive number representing the amount lost.

A Concrete Shopping Scenario

A high-definition television originally priced at $600 is discounted to $450 during a seasonal clearance sale. What is the percentage decrease in price?

1. Calculate the dollar reduction: $600 - $450 = $150 reduction.
2. Divide by the starting baseline: $150 ÷ $600 = 0.25.
3. Multiply by 100: 0.25 × 100 = 25%.

The price dropped by exactly 25%.

Key Differences Between Reductions and Increases

An interesting mathematical property that often catches people by surprise is that a percentage decrease does not have an equal opposite effect. If a $100 stock falls by 50%, it drops to $50. But for that $50 stock to return to $100, it must increase by 100%! Because the baseline changed from $100 to $50, the recovery percentage is twice as large.

Use our interactive Percentage Decrease Calculator to compute drops in prices, weights, and metrics quickly.