Work out the sale price and how much you save with a percentage discount, including stacked discounts ("an extra 10% off") and sales tax.
How to calculate a discount
Sale price = original price × (1 − discount ÷ 100)
Savings = original price − sale price
Worked examples
- An $80 item at 25% off costs $80 × 0.75 = $60. You save $20.
- With an extra 10% off at checkout, the price becomes $60 × 0.90 = $54.
- Adding 8.25% sales tax to $60 gives $64.95.
Stacked discounts do not simply add up
"25% off plus an extra 10%" is not 35% off. The second discount applies to the already-reduced price, so the total discount is 1 − (0.75 × 0.90) = 32.5%. The order of the two discounts does not change the final price.
Is it really a deal?
- Compare the final price, not the percentage. 40% off an inflated price can still cost more than a regular price elsewhere.
- Check price per unit for groceries and household goods.
- Remember shipping and tax, which can wipe out a small discount.
- Ask whether you would buy it at full price. If not, the "saving" is still spending.
Frequently asked questions
How do I find the original price from a sale price?
Divide the sale price by (1 − discount). $60 after 25% off was $60 ÷ 0.75 = $80.
Is sales tax charged on the original or discounted price?
Usually on the discounted price for store discounts. Manufacturer coupons can be treated differently in some states.
Related tools
Results are estimates for planning and education only. They are not financial, tax, legal or medical advice. Check important numbers with a qualified professional.