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Calculate reverse percentages easily. Find the original value from a final value after a percentage increase or decrease with our free calculator.
| Formula | Purpose | Notes |
|---|---|---|
| Original = Final ÷ (1 + P/100) | Reverse a percentage increase | Multiplier = 1 + P/100 |
| Original = Final ÷ (1 − P/100) | Reverse a percentage decrease | Multiplier = 1 − P/100 |
| Change = Final − Original | The actual amount added or removed | — |
A Reverse Percentage Calculator helps you find the original value when you know the final value and the percentage change. It is useful when a price, amount, score, or other value has already increased or decreased by a percentage.
For example, if a price is now $120 after a 20% increase, what was the original price? You cannot simply subtract 20% from $120. You need to reverse the percentage correctly.
Our free reverse percentage calculator makes this calculation quick and simple. Enter the final value, percentage, and choose an increase or decrease. The calculator finds the original value, multiplier, and change.
The reverse percentage formula depends on whether the final value came from an increase or decrease.
Original Value = Final Value ÷ (1 + Percentage ÷ 100)
The multiplier is:
Multiplier = 1 + Percentage ÷ 100
For a 20% increase:
Multiplier = 1 + 20 ÷ 100 = 1.20
Original Value = Final Value ÷ (1 − Percentage ÷ 100)
The multiplier is:
Multiplier = 1 − Percentage ÷ 100
For a 20% decrease:
Multiplier = 1 − 20 ÷ 100 = 0.80
The change is calculated as:
Change = Final Value − Original Value
This reverse calculation formula works because the final value represents the original value after the percentage change has already been applied.
Suppose a product costs $120 after a 20% increase.
First, calculate the multiplier:
Multiplier = 1 + 20 ÷ 100
Multiplier = 1.20
Now find the original price:
Original Value = 120 ÷ 1.20
Original Value = $100
The change is:
Change = 120 − 100
Change = $20
So, the original price was $100.
For a reverse percentage decrease, suppose a product costs $80 after a 20% decrease.
Multiplier = 1 − 20 ÷ 100
Multiplier = 0.80
Original Value = 80 ÷ 0.80
Original Value = $100
Change = 80 − 100
Change = −$20
This shows why reverse percentages must use the correct multiplier instead of simply adding or subtracting the percentage from the final number.
You can also perform a reverse percentage calculation in Excel.
For a percentage increase, use:
=Final_Value/(1+Percentage/100)
For a percentage decrease, use:
=Final_Value/(1-Percentage/100)
For example, if 120 is in cell A1 and 20% is in B1, an increase calculation can use:
=A1/(1+B1)
If B1 contains the percentage as 20%, Excel already stores it as 0.20.
A Reverse Percentage Calculator is a simple way to work backward from a final value to its original value. The key is to divide the final value by the correct percentage multiplier.
For an increase, use Final ÷ (1 + Percentage/100). For a decrease, use Final ÷ (1 − Percentage/100).
Our free online calculator removes the need for manual math and gives you a fast, clear reverse percentage calculation.
Divide the final value by the percentage multiplier. For an increase, use Final ÷ (1 + Percentage/100). For a decrease, use Final ÷ (1 − Percentage/100).
For a 20% increase, divide the final value by 1.20. For a 20% decrease, divide the final value by 0.80.
Because the original percentage was calculated from the original value, not the final value. Reverse percentage math must undo the percentage multiplier.
Use =Final/(1+Percentage) for an increase or =Final/(1-Percentage) for a decrease when the percentage cell is formatted as a percentage.
Yes. Convert the percentage into a multiplier and divide the final value by that multiplier.
A 100% decrease produces a multiplier of zero. Therefore, the original value cannot be recovered from the final value using this reverse percentage calculation.