Reverse Percentage Calculator

A reverse percentage calculator helps you work backwards from a final value to find out what the original amount was before a percentage increase or decrease occurred. Whether you're trying to determine the original price of a discounted item or calculate a pre-tax value, this tool does the hard math instantly.

How It Works

Unlike standard percentage calculations that apply a change to an original value, reverse percentages undo that change. The calculator uses formulas like:

Original Value = Final Value / (1 + Percentage/100) for increases
Original Value = Final Value / (1 - Percentage/100) for decreases

You only need to know two things:

The final value (after the percentage change)
The percentage of the increase or decrease

The calculator handles the rest.

Common Use Cases

Shopping: Find out the original price before a discount.
Finance: Determine the pre-tax or pre-fee amount of a transaction.
Salary: Backtrack from your net salary to gross income before deductions.
Sales: Uncover the cost before a markup was added.

Reverse Percentage Examples & Explanations

Example 1: Shopping Discount

Question:
You bought a jacket for $80 after a 20% discount. What was the original price?

How to solve:
Since it's a percentage decrease, we use:

Original Price = 80 / (1 - 0.20) = 80 / 0.8 = 100

Answer: The original price was $100.

Explanation:
A 20% discount means you paid 80% of the original price. Dividing $80 by 0.8 reveals the full value.

Example 2: Sales Tax (Percentage Increase)

Question:
An item costs $107 after 7% sales tax. What was the price before tax?

How to solve:
This is a percentage increase:

Original Price = 107 / (1 + 0.07) = 107 / 1.07 ≈ 100

Answer: The pre-tax price was $100.

Explanation:
Sales tax added 7% to the original price. Divide the total by 1.07 to remove the tax.

Example 3: Salary After Deduction

Question:
You received $1,500 after a 25% tax deduction. What was your gross salary?

How to solve:
This is a percentage decrease:

Gross Salary = 1500 / (1 - 0.25) = 1500 / 0.75 = 2000

Answer: Gross salary was $2,000.

Explanation:
A 25% deduction means you keep 75% of your pay. Divide by 0.75 to find the full amount.

Example 4: Markup on a Product

Question:
A product is sold for $180 after a 20% markup. What was the original cost price?

How to solve:
This is a percentage increase:

Cost Price = 180 / (1 + 0.20) = 180 / 1.2 = 150

Answer: Cost price was $150.

Explanation:
A 20% markup means the final price is 120% of the cost. Divide by 1.2 to go backwards.

Quick Tip:

If the percentage is an increase, divide by (1 + percentage/100)
If it’s a decrease, divide by (1 - percentage/100)