Discount Calculator
Work out a sale price, find the original price hiding behind a discount, or see what happens when you stack two or three discounts on top of each other.
Formula and method
Discounted price: original × (1 − percent ÷ 100).
Original price: final ÷ (1 − percent ÷ 100). Undefined at exactly 100%.
Discount percentage: ((original − final) ÷ original) × 100.
Stacked discounts apply one after another to the running price. They never simply add up, whatever the sign in the shop window implies.
Worked example
A supplier lists an item at €100 and offers 20% off, then another 10% for settling within 7 days.
First: €100 − 20% = €80. Then: €80 − 10% = €72.
The effective discount is (100 − 72) ÷ 100 = 28%, not the 30% you'd expect if you just added the two numbers.
FAQ
Frequently asked questions
How do I calculate a discounted price?
Multiply the original price by the discount percentage to get the reduction, then subtract it. €100 with 20% off is €100 − €20 = €80.
How do I find the original price from a discounted price?
Divide the discounted price by (1 − discount ÷ 100). €80 after a 20% discount started life at €80 ÷ 0.8 = €100.
Do stacked discounts just add up?
No, and this catches people out. Each discount applies to the price left after the last one. 20% then 10% off €100 lands at €72 - an effective discount of 28%, not 30%.
Why can't a 100% discount be reversed?
Because it leaves a final price of zero, and every original price you could name would also end up at zero. There's no way back from that.
Does this calculator include VAT?
No. Keep your prices consistent - either all including VAT or all excluding it. Use the VAT calculator if you need to switch between the two.
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