🔢 Reverse Percentage Calculator

PercentageCalculatorFree.com Team Last Updated: January 24, 2026

Find the original value before a percentage increase or decrease was applied.

Original Value

Final Value: *

Percentage: *

Original Value: *

How Reverse Percentage Works

What is "Reverse Percentage"?

This calculation helps you find the original value of a number before a (like a markup or tax) was added. It allows you to "reverse" the calculation when you only know the final amount and the percentage that was added to it.

Formula

Reverse Percentage Formula (After Increase)

Original Value = Final Value / (1 + Increase% / 100)

Final Value = The amount after the increase

Increase% = The percentage that was added

Original Value = The starting number you're looking for

Step-by-Step Example

Problem: A product costs $120 after a 20% markup. What was the original cost?

Given:
Final Value = $120
Markup = 20%

Step 1: Convert increase to a multiplier
1 + (20 / 100) = 1.20

Step 2: Divide the final value by the multiplier
Original = $120 / 1.20 = $100

Answer: The original price was $100.

🎯 Tips & Common Mistakes

Don't just subtract the percentage: If a price increased by 20%, you cannot find the original by subtracting 20% from the final price. This is because 20% of the final price is larger than 20% of the original.
Markup vs. Discount: This formula assumes an increase. If you are calculating for a discount, you would use (1 - Percentage / × 100) as your divisor.

Finding the Original

Reverse percentage helps you find the original value before a percentage was applied. It's essential for removing taxes from prices, finding pre-discount amounts, and recovering original costs.

The Reverse Formula

After Increase: Original = Final ? (1 + Rate/100)
After Decrease: Original = Final ? (1 - Rate/100)
Example: $115 after 15% increase → $115 / 1.15 = $100

Tax-Inclusive Pricing

Many countries display tax-inclusive prices. To find the pre-tax amount: divide by (1 + tax rate). At 8% tax, a \ total means \ base price. This is not the same as subtracting 8% from $80? That would give $73.60, which is incorrect.

❓ Frequently Asked Questions

What is a reverse percentage?

It is finding the original value after a percentage increase or decrease has been applied. You are 'reversing' the change.

How do I calculate the original price after a discount?

Divide the current price by (1 - discount rate as a decimal). If a shirt is after a 20% discount, calculate 20 / 0.8 = .

Why can't I just add the percentage back?

Because the percentage was taken from the *original* higher amount, not the new lower amount. Adding 20% to () won't get you back to .

🔍 Authoritative References

For more information about basic percentage calculations, consult these trusted sources:

National Council of Teachers of Mathematics - Mathematics education standards
Math is Fun - Clear mathematical explanations and examples