Percentage Decrease Calculator
Find the percentage drop between two values.
Starting value before the decrease.
Value after the decrease.
Percentage decrease
20%
Percent drop relative to the original value.
New / final value
80
Value after the decrease.
Original value
100
Decrease amount
20
Remaining percentage
80%
Mode
Original value to new value
Formula used
Percentage Decrease = (Original Value − New Value) ÷ Original Value × 100
(100 − 80) ÷ 100 × 100
Percentage Decrease Formulas
Decrease Amount
Decrease Amount = Original Value − New Value
Percentage Decrease
Percentage Decrease = (Original Value − New Value) ÷ Original Value × 100
New Value After Decrease
New Value = Original Value × (1 − Percentage Decrease ÷ 100)
Reverse Original Value
Original Value = New Value ÷ (1 − Percentage Decrease ÷ 100)
Remaining Percentage
Remaining Percentage = 100% − Percentage Decrease
Variable Explanations
Original value
Starting value before the decrease.
New value
Value after the decrease.
Decrease amount
Original value minus new value.
Percentage decrease
Decrease amount as a percent of the original value.
Remaining percentage
Percent of the original value still left after the decrease.
Reverse decrease
Finding the original value from the final value.
What Percentage Decrease Means
Relative drop
Percentage decrease measures how much a value fell relative to its starting point.
Original is the base
The original value is the denominator in the formula.
Remaining value
A 25% decrease means 75% remains.
Everyday use
Common in discounts, price drops, sales, statistics, and finance.
Not percentage points
Percentage decrease is not the same as subtracting percentage points.
Increase check
If the new value is higher, the change is an increase.
Worked Examples
Decrease from 100 to 80
Formula: (100 − 80) ÷ 100 × 100
Answer: 20%
The value dropped by 20, which is 20% of 100.
Decrease from 250 to 200
Formula: (250 − 200) ÷ 250 × 100
Answer: 20%
The decrease amount is 50.
Price after 25% decrease from 80
Formula: 80 × (1 − 25 ÷ 100)
Answer: 60
A 25% decrease means 75% remains.
Original from final 60 after 25% decrease
Formula: 60 ÷ 0.75
Answer: 80
Reverse decrease divides by the remaining percentage.
Decrease amount and remaining percent
Formula: 100 − 35 = 65
Answer: 65% decrease, 35% remains
Remaining percent is 100% minus decrease percent.
New value higher than original
Formula: 120 compared with 100
Answer: 20% increase
This is not a decrease.
20% decrease then 20% increase
Formula: 100 → 80 → 96
Answer: Not back to 100
The second percent uses a different base.
Decimal value example
Formula: (12.5 − 10) ÷ 12.5 × 100
Answer: 20%
Decimals work the same way.
Percentage Decrease vs Percentage Change
Percentage decrease
Percentage decrease is a positive percent drop when the new value is lower than the original. Example: 100 to 80 is a 20% decrease.
Percentage change
Percentage change can be positive or negative. Example: 80 to 100 is a 25% increase because the base is now 80.
Reverse Percentage Decrease
Reverse percentage decrease finds the original value before a decrease. Do not simply add the percentage back to the final value. If 60 is the value after a 25% decrease, then 60 is 75% of the original. Original value = 60 ÷ 0.75 = 80.
Common Use Cases
Common Percentage Decrease Mistakes
Understanding Your Results
Percentage decrease
Percent drop relative to the original value.
Decrease amount
Absolute amount lost or removed.
New value
Value after the decrease.
Remaining percentage
Percentage of the original still left.
Reverse original value
Estimated starting value before the decrease.
Frequently Asked Questions
Related tools