Reverse Percentage Calculator
Work backward from a final value and percentage to find the original number before the increase or decrease.
Reverse Percentage
Find original value before a % was applied
V / (1 + P/100)
V / (1 - P/100)
No calculations yet.
How to Calculate
Original = Final ÷ (1 + P/100) [increase] or Final ÷ (1 − P/100) [decrease]
If a final value incorporates an increase of P percent, the original value is calculated by dividing the final value by (1 + P ÷ 100). If it incorporates a decrease of P percent, divide by (1 − P ÷ 100). This reverses the percentage scaling factor precisely.
* Example: Final $60 after 20% increase → Original $50
Step-by-Step Manual Calculation Guide
Step 1: Identify whether the percentage was an increase or decrease.
Step 2: Create the decimal scaling factor: (1 + P/100) for increases or (1 - P/100) for decreases.
Step 3: Divide the final known amount by your scaling factor to reveal the original baseline.
Real-World Industry Applications
Tax Auditing & Accounting
Finding the original pre-VAT price of a receipt total of $115 when VAT is 15% ($115 ÷ 1.15 = $100 original).
Retail Discount Recovery
Determining the original list price of a discounted item purchased for $80 after a 20% sale ($80 ÷ 0.80 = $100 list price).
Payroll Base Salary Calculation
Uncovering a worker's base pay prior to a 10% performance bonus payout.
Reverse Percentage Worked Examples
How it Works
Reverse percentage calculations allow you to work backward from a final total amount to find the original pre-tax, pre-discount, or pre-raise starting value. This tool is invaluable when auditing receipts, determining original wholesale costs before tax additions, or calculating base salaries from total compensation.
Related Calculators
Frequently Asked Questions
How do I calculate the original price before a discount?
Divide the discounted price by (1 - discount percentage as a decimal). For example, if a jacket cost $60 after a 25% discount, divide $60 by 0.75 to get $80.
Why can't I just add the percentage back to the final number?
Because percentages scale relative to the base they are applied to. Adding 20% to $80 gives $96, not the true original $100 price, because 20% of $80 is smaller than 20% of $100.
Does reverse percentage work for calculating pre-tax amounts?
Yes, to find the pre-tax price, divide the total tax-inclusive price by (1 + tax rate as a decimal).