Why discount calculations matter

Retailers often advertise “20% off” or a fixed dollar reduction. Knowing how to calculate the final price helps you compare deals and understand how much you actually save.

Formulas

Percentage discount

Discount amount = Original price × (Discount % ÷ 100) Final price = Original price − Discount amount

Alternatively:

Final price = Original price × (1 − Discount % ÷ 100)

Fixed amount discount

Final price = Original price − Fixed discount

Worked examples

Example 1: A jacket costs $100 with 20% off.

Discount = 100 × 0.20 = $20

Final price = 100 − 20 = $80

Example 2: An item is $49.99 with $10 off.

Final price = 49.99 − 10 = $39.99

Example 3: Stacked percentage discounts are not simply added. 20% off then 10% off on the reduced price is not the same as 30% off the original price.

Common mistakes

  • Subtracting the percentage number from the price (for example treating 20% off $100 as $80 without converting 20% to 0.20 first — the result can still be right by coincidence, but the method is unclear).
  • Assuming two successive discounts can be added together.
  • Forgetting taxes, shipping or fees that may still apply to the discounted price.

FAQ

Does a larger percentage always mean a better deal?
Not always. Compare the final price, not only the advertised percentage, especially when original “list” prices differ.

Calculate sale prices instantly:

Open Discount Calculator