Guides/Percent change decrease

How to calculate percent change (decrease)

Percent decrease measures how much a value fell relative to its starting point — the mirror of percentage increase.

Formula

Percent decrease = ((old − new) ÷ old) × 100

Same as absolute value of ((new − old) ÷ old) × 100 when new < old. Old cannot be zero. Increase guide:percentage increase. Retail framing:decrease & discount math.

Worked examples

1. Price: $80 → $60. Drop = 20; 20÷80×100 = 25% decrease.
2. Traffic: 10,000 visits → 8,500. (1500÷10000)×100 = 15% decrease.
3. Weight metric: 90 kg → 81 kg. 9÷90×100 = 10% decrease.
4. Not the same as “25% off” labeling confusion: percent off is a planned discount on list price; percent decrease compares two observed values —percent off vs percent of.

Common mistakes

• Dividing by the new value instead of the old one.
• Expecting −25% then +25% to restore the start (it does not).
• Mixing percentage points with percent change.

Calculate free

Use thePercentage CalculatorIncrease/Decrease mode. Two-step stacks:compound two-step changes.