How to use this tool
- Enter the original price and the discount percentage.
- Add a second discount if there is an extra code or clearance offer.
- Add tax if your prices are shown before tax, as in most US shops.
Stacked discounts are not added together
"Take an extra 10% off sale prices" sounds like 20% + 10% = 30%, but the second discount is taken from the already reduced price. On a $100 item, 20% off gives $80, then 10% off $80 is $8, leaving $72. That is 28% off in total. The calculator shows the true combined discount.
Tax and discounts
In the US, sales tax is usually added at the till on the discounted price. In the UK and India, shelf prices already include VAT or GST, so leave the tax box at zero.
Is the "was" price real?
In the US, FTC guidance says a former price should be one the item was genuinely sold at for a reasonable period. UK pricing guidance is similar. If a discount looks too good, compare prices at other shops before buying.
Scaling a price, recipe or measurement? The proportion calculator solves a/b = c/x for you.
Frequently asked questions
How do I calculate 20% off?
Multiply the price by 0.8. For example, 20% off £50 is £40.
Is 20% off plus 10% off the same as 30% off?
No. Applied one after another they make 28% off.
How do I work out the original price from a sale price?
Divide the sale price by (1 − discount). A $60 item at 25% off was originally $60 ÷ 0.75 = $80.
Is tax charged before or after the discount?
Usually after. Tax is calculated on the price you actually pay.
Sources and references
- Federal Trade Commission: Guides Against Deceptive Pricing (16 CFR 233)
- CTSI: Guidance for Traders on Pricing Practices (UK, April 2026)