How to Calculate Percentage Decrease
Last updated 2026-09-11
Percentage decrease measures how much a value has dropped, expressed as a fraction of its starting point — common for price drops, weight loss, or performance decline.
Subtract the new value from the old value
This gives you the raw decrease in units.
Divide by the old value
This expresses the drop as a fraction of the starting point.
Multiply by 100
Full formula: ((Old − New) ÷ Old) × 100.
Example
A product's price drops from $80 to $60. Decrease = ((80 − 60) ÷ 80) × 100 = 25%.
Important Considerations
- If the new value is larger than the old one, you want percentage increase instead.
- A 100% decrease means the value reached zero — it cannot decrease further in percentage terms.
- Repeated percentage decreases compound the same way increases do — they don't simply add together.
Frequently Asked Questions
- What if the value increased instead of decreased?
- Use the percentage increase formula: ((New − Old) ÷ Old) × 100.
- Can percentage decrease be more than 100%?
- No — a value can drop at most to zero, which is a 100% decrease. Anything beyond that isn't a percentage decrease of the original value.