How to calculate a discount
Multiply the price by the discount rate to get the savings, then take that off the price. Or do it in one step: sale price = price × (1 − discount). 25% off $80 is $80 × 0.75 = $60, a $20 saving.
For a dollar discount, just subtract. $15 off $80 is $65, which works out to 18.75% off.
Stacked discounts
When a store offers an extra 10% off sale items, the second discount comes off the price that's already reduced. So 25% off and then 10% off isn't 35% off. It's $80 × 0.75 × 0.9 = $54, which is 32.5% off in total.
The order of two percentage discounts doesn't change the result. A dollar coupon does: $15 off then 10% off $80 is $58.50, but 10% off then $15 off is $57. Check which way the store applies it.
Finding the percent off
Percent off = (original − sale price) ÷ original × 100. A jacket cut from $120 to $84 is $36 off, which is 30%. It's a quick way to check whether a sale is as good as the sign says.
Sales tax is usually charged on the price after the discount, so the tax goes down too.
Pricing a sale on your own products
If you sell things yourself, start from your margin before you pick a discount. Say a product sells for $100 and costs you $50. At 30% off you earn $20 instead of $50 on each sale, so you need 2.5 times as many sales just to make the same profit.
Smaller discounts, bundles or a free extra often protect your profit better than a big percentage off.
Common discounts at a glance
To get a sale price fast, multiply by what's left after the discount:
- 10% off: × 0.9
- 15% off: × 0.85
- 20% off: × 0.8
- 25% off: × 0.75
- 30% off: × 0.7
- 40% off: × 0.6
- 50% off: half price, × 0.5
Frequently asked questions
How do I calculate 20% off?
Multiply the price by 0.8. 20% off $45 is $36, and you save $9.
How do I find the percent off between two prices?
Subtract the sale price from the original, divide by the original and multiply by 100. $50 down to $35 is 30% off.
Is 20% off plus 10% off the same as 30% off?
No. The second discount comes off the reduced price, so it's 28% off in total.
Is sales tax charged before or after a discount?
For store discounts, most US states charge sales tax on the discounted price. Manufacturer coupons can be treated differently, depending on the state.
How do I work out a discount in my head?
Find 10% by moving the decimal point one place left, then multiply. For 30% off $70, 10% is $7, so you save $21 and pay $49.