How to calculate a discount
sale price = original price × (1 − discount ÷ 100)
savings = original price − sale price
Example: a jacket costs $89.99 with 25% off. Sale price = 89.99 × 0.75 = $67.49, so you save $22.50.
Stacked discounts: why 30% + 20% is not 50%
Shops sometimes offer an extra discount “on top of” sale prices, for example 30% off plus an extra 20% at checkout. The second discount applies to the already reduced price:
final price = price × (1 − d1 ÷ 100) × (1 − d2 ÷ 100)
On a $100 item: 100 × 0.70 = $70, then 70 × 0.80 = $56. The total discount is 44%, not 50%. Enter the second percentage in the “extra discount” field and the calculator shows the combined discount.
Finding the percent off
If you know the original price and the sale price, switch to “Discount % from original and sale price”:
discount % = (original − sale) ÷ original × 100
Example: a $89.99 item now costs $59.99. (89.99 − 59.99) ÷ 89.99 × 100 = 33.34% off.
Quick mental math
- 10% off: move the decimal point one place left and subtract. $45 − $4.50 = $40.50.
- 25% off: divide by 4 and subtract, or multiply by 0.75.
- 50% off: half price.
- “Buy one, get one 50% off”: equals 25% off both items when they cost the same.
- “3 for 2”: about 33% off per item.
Is it really a good deal?
- Compare with the regular price elsewhere. A 40% discount on an inflated “was” price may be worse than another shop’s normal price.
- Watch the sales tax. In the US, sales tax is calculated on the discounted price and added at checkout; in Europe, displayed prices already include VAT. See the VAT calculator.
- Check shipping and return costs, which can wipe out a small discount.
- Price per unit: a bigger pack with a discount is only better if the price per unit is lower.
For sellers
If you run a shop, remember that discounts come out of your margin. A 20% discount on a product with a 40% margin halves your profit per item. Check the effect with the profit margin calculator before you plan a sale.
Discounts and sales tax
In the US and Canada, prices are usually shown before sales tax, and tax is added at checkout on the discounted price. A $100 item at 30% off costs $70, and with 8% sales tax you pay $75.60. In Europe and the UK, shelf prices include VAT, so a discount applies to the price you see. If you are a business buying at a discount, remember that the VAT you can reclaim is based on the discounted price too.
Sales events
During Black Friday, Cyber Monday, Prime Day or January sales, discounts can look bigger than they really are. Some retailers raise the "was" price shortly before a sale, so a 50% discount may only be 20% off the usual price. Price tracking tools and browser extensions show a product’s price history, which helps you judge whether a deal is genuine. Set a budget beforehand, and use the calculator to compare the real price after all discounts, including shipping.
Frequently asked questions
How do I calculate 30% off?
Multiply the price by 0.70. For example, 30% off $80 is $56, and you save $24.
How do I calculate the original price from a sale price?
Divide the sale price by (1 − discount ÷ 100). If $60 is the price after 25% off, the original was $60 ÷ 0.75 = $80.
Are two discounts of 20% the same as 40%?
No. Two 20% discounts give a total of 36% off, because the second applies to the reduced price.
How do I find the discount percentage?
Subtract the sale price from the original price, divide by the original price and multiply by 100.
Is sales tax added before or after the discount?
In the US, sales tax is calculated on the price after the discount. In the EU and UK, shelf prices include VAT, so the discount applies to the full price including VAT.
Can I use other currencies?
Yes. Choose dollars, euros, pounds or no symbol in the currency field.
Last reviewed: 2026-10-06. Results are estimates for information only.