Percentage decrease shows how much a value has fallen relative to its original amount. It is useful for price reductions, declining sales, weight loss, lower expenses, and changes in measurements.
Percentage decrease formula
Percentage decrease = (Original value − New value) ÷ Original value × 100
How to calculate a percentage decrease
- Subtract the new value from the original value.
- Divide the decrease by the original value.
- Multiply the result by 100.
- Add the percent sign.
Example: price decrease
A product falls from $80 to $68. The decrease is $12. Divide 12 by the original price of 80 to get 0.15, then multiply by 100. The price decreased by 15%.
Example: declining monthly cost
A monthly bill drops from $250 to $210. The decrease is $40. Calculate 40 ÷ 250 × 100 to get a 16% decrease.
Find the new value after a percentage decrease
To reduce a number by a known rate, multiply it by the percentage that remains:
New value = Original value × (1 − rate ÷ 100)
For example, decreasing 150 by 12% leaves 88%, so 150 × 0.88 = 132.
Find the original value
If you know the result after a decrease, divide it by the remaining multiplier. A value of 144 after a 20% decrease represents 80% of the original: 144 ÷ 0.80 = 180. See the complete reverse percentage guide for more examples.
Percentage decrease vs percentage difference
Percentage decrease has a clear starting value and measures a downward change from it. Percentage difference compares two values without treating either as the starting point. Choosing the wrong denominator can produce a different result.
Common mistakes
- Dividing by the new value instead of the original.
- Subtracting in the wrong direction and reporting a negative decrease.
- Confusing percentage points with percent change.
- Assuming equal increases and decreases cancel each other.
Frequently asked questions
Can a percentage decrease exceed 100%?
Not when both values are nonnegative and the new value cannot fall below zero. In contexts that allow negative values, interpretation requires more care.
Does a 20% decrease followed by a 20% increase return to the start?
No. Starting at 100 gives 80 after the decrease, then 96 after increasing 80 by 20%.
How do I calculate percentage increase instead?
Subtract the original from the new value, divide by the original, and multiply by 100. See our percentage increase guide.