Whether you're shopping in a sale or pricing products, discount calculations are essential daily math. Here are all the formulas you need.
Percentage Off Formula
Discount Amount = Original Price × (Discount % / 100)
Final Price = Original Price - Discount Amount
Example: $80 item at 25% off
Discount = $80 × 0.25 = $20
Final Price = $80 - $20 = $60
Quick One-Step Formula
Final Price = Original Price × (1 - Discount%/100)
Example: $80 at 25% off:
$80 × (1 - 0.25) = $80 × 0.75 = $60
Finding the Discount Percentage
If you know original and sale price:
Discount % = ((Original - Sale) / Original) × 100
Example: Regular price $120, sale price $90:
((120 - 90) / 120) × 100 = (30/120) × 100 = 25%
Multiple Discounts (Stacking)
Two discounts don't simply add — they compound.
Example: 20% off, then an additional 10% off:
First discount: $100 × 0.80 = $80
Second discount: $80 × 0.90 = $72
Total saved: $28 (not $30). Equivalent to a single discount of 28%.
Formula: Combined discount = 1 - (1 - d1)(1 - d2)
Working Backwards: Finding Original Price
If you know the sale price and discount:
Original = Sale Price / (1 - Discount%/100)
Example: Item costs $63 after 30% off:
$63 / 0.70 = $90 original price
Sale + Tax Calculation
Always apply discount before tax:
1. Apply discount: $100 × 0.75 = $75
2. Apply tax: $75 × 1.08 = $81 (with 8% tax)
Never apply tax first, then discount — you'll calculate incorrectly.
Retail Markup vs. Discount
A 50% markup is NOT the same as a 50% discount:
- 50% markup: Cost $60 → sell for $90
- 50% discount: Price $90 → sell for $45
Markup is calculated on cost; discount is calculated on selling price.
Use our Discount Calculator to instantly calculate any sale price, discount amount, or original price.