How to use the discount calculator
- Enter the original (list) price and the advertised percent off.
- If a store offers “an extra 10% off the sale price”, put that in Extra discount. Leave it blank otherwise.
- Add your local sales tax rate if you want the checkout total. Leave it blank to compare pre-tax prices.
- Press Calculate to see the sale price, the dollars saved, the effective discount, and the total with tax.
Comparing two offers: “Buy one, get one 50% off” on two equally priced items works out to 25% off both. A fixed coupon such as $20 off $100 is 20% off, but the same $20 on a $250 item is only 8%. Converting every offer into an effective percentage, or better, a final price, is the simplest way to see which deal really saves more. It's also worth checking the “original” price against what the item usually sells for.
How it's calculated
Savings = price − sale price
Total = sale price × (1 + tax% ÷ 100)
Stacked discounts multiply; they don't add. “30% off plus an extra 10%” isn't 40% off. The second discount applies to the already-reduced price, so the effective discount is 1 − 0.70 × 0.90 = 37%. The effective discount line shows this combined figure so you can compare offers fairly.
Sales tax is charged on the discounted price in most US states, so the tool applies tax after all discounts.
Worked example
Simple sale: a $60 pair of shoes at 25% off costs 60 × 0.75 = $45, a saving of $15.
Stacked coupon with tax: a $200 coat is 30% off, with an extra 10% at checkout and 8% sales tax.
- After 30% off: 200 × 0.70 = $140
- After the extra 10%: 140 × 0.90 = $126 (you save $74, an effective 37%)
- Tax: 126 × 0.08 = $10.08, so the total is $136.08
FAQ
How do I calculate 20% off a price?
Multiply the price by 0.80. For example, 20% off $45 is 45 × 0.80 = $36, a saving of $9.
Is 30% off plus 20% off the same as 50% off?
No. The second discount applies to the reduced price, so the result is 1 − 0.70 × 0.80 = 44% off, not 50%.
Does the order of two discounts matter?
Not for percentage discounts. Multiplication gives the same result in any order. It does matter when one discount is a fixed dollar amount.
Is sales tax charged before or after the discount?
In most US states sales tax is charged on the discounted selling price, which is how this calculator works. Some manufacturer coupons are taxed differently, so check your receipt.