~/tools/reverse-discount $ run retail --reverse-discount
Original Price Before Discount Calculator
Find what an item cost originally before a percentage markdown was applied.
To find the original price before a discount, divide the discounted sale price by the decimal representation of the percentage you actually paid (1 - Discount% / 100).
Original Pre-Sale Price:
$150
Exact Cash Saved:
$30
// How to Reverse a Discount (Work Backward)
Finding the original pre-discount price is useful when shops only display the percentage off and your final bank swipe amount, but do not state what the base starting price was. By scaling the price paid back up to 100%, you get the complete retail picture.
Mathematical Formula:
Original Price = Discounted Price / (1 - Discount% / 100)
Worked Example: Paid $120 after 20% off
Suppose you paid $120 for an item during a 20% off store sale.
1. Calculate the percentage you actually paid: 100% - 20% = 80% (or 0.80 as a decimal).
2. Divide the price paid by the decimal fraction: $120 / 0.80 = $150.
The item's original retail price before the sale markdown was exactly $150.
// Frequently Asked Questions
▸Why is reverse discount calculation different from standard percentage addition?
This is a common commercial error! If an item has a 20% discount, adding 20% back to the final discounted price WILL NOT give you the correct original price. For example: 20% of $120 is $24; adding $24 gives you $144, which is incorrect. The correct original price is $150.
▸What is a practical use of a reverse discount?
It is frequently used by financial auditors to reconcile merchandise values, and by savvy shoppers to calculate the actual inflation or markup applied before clearance sales.
▸Can I use this calculator for sales tax extraction?
While mathematically similar, sales tax (VAT) addition works on top of a 100% base price (making gross total e.g. 113%). We have a dedicated 'Tax Calculator' that is optimized specifically for adding and extracting sales taxes correctly!