How Discounts & Sales Pricing Work
Whether shopping during Black Friday, evaluating clearance store tags, or analyzing wholesale invoices, understanding how discount percentages affect bottom-line costs helps avoid deceptive markdowns. A discount is the reduction of a product's list price by a specified percentage or fixed cash amount.
The Mathematical Discount Formulas
The standard steps to determine final price after markdowns and tax are:
Discounted Price = Original Price - Savings
Final Price = Discounted Price × (1 + Sales Tax / 100)
Step-by-Step Example Calculation
Suppose an electronic item has an original sticker price of $120.00. The store offers a 25% discount, and the local state sales tax rate is 7%:
- Calculate total savings: \(\$120.00 \times (25 / 100) = \$30.00\).
- Calculate discounted subtotal: \(\$120.00 - \$30.00 = \$90.00\).
- Calculate sales tax on subtotal: \(\$90.00 \times 0.07 = \$6.30\).
- Sum to find final checkout cost: \(\$90.00 + \$6.30 = \$96.30\).
You save \$30.00 on the item, paying \$96.30 out of pocket after tax.
Common Pitfall: Double Discounts
Retailers often advertise "20% off plus an extra 10% off." This is not equal to a flat 30% discount! The second 10% discount applies to the already discounted price, resulting in an effective 28% total discount (\(1 - 0.80 \times 0.90 = 0.28\)).
Frequently Asked Questions (FAQ)
Is sales tax charged before or after discount?
In almost all jurisdictions, sales tax is assessed on the discounted selling price (subtotal), rather than the original manufacturer's suggested retail price (MSRP).
How do I convert a percentage off to a multiplier?
Subtract the percentage from 100 and divide by 100. For instance, 30% off means you pay 70% of the price (multiplier of 0.70).