Step-by-step guide: How to Calculate a Discount and the Final Sale Price
How to use the Discount Calculator
- Enter the original price and, if you like, choose a currency symbol for the results.
- Enter the discount as a percentage, or switch the type to Amount off for a fixed reduction such as “£15 off”.
- If a second discount applies to the already reduced price, enter it in the optional field.
- Add the sales tax or VAT rate if it is charged on top of the price shown, as in most of the United States.
- Read the final price, the amount saved and the effective overall discount. The steps underneath show each stage.
Example: why 25% + 10% is not 35% off
A coat costs 80. It is reduced by 25%, and a coupon gives an extra 10% off the sale price.
80 × (1 − 0.25) = 60
60 × (1 − 0.10) = 54
You pay 54 and save 26, an effective discount of 32.5% — not 35%, because the second discount applies to the already reduced price. With 8.25% sales tax, the checkout total is 54 × 1.0825 = 58.46.
How stacked discounts and tax are applied
Discounts are applied in the order listed. A percentage discount multiplies the current price by (1 − rate). An amount discount subtracts a fixed sum. Tax, if given, is applied last to the discounted price, which is how sales tax is normally calculated in the United States and Canada.
final = ((price after discounts) × (1 + tax ÷ 100))
effective discount = (original − price after discounts) ÷ original × 100
The effective discount excludes tax so it describes the reduction the retailer is actually giving.
Reading shop offers carefully
- “Up to 70% off” means some items are discounted by 70%; most may be reduced far less.
- “Buy one, get one half price” on two equally priced items is a 25% discount overall.
- When an amount-off coupon and a percentage discount can be used in either order, applying the percentage first and the fixed amount second gives a lower price — though shops usually decide the order for you.
Limitations to keep in mind
- Retailers may round at different stages, so totals can differ by a cent or two from a receipt.
- Tax rules vary: some places include VAT in displayed prices, some exempt certain goods, and shipping may be taxed separately.
- The calculator assumes discounts apply in the order entered.
How your data is handled
The calculation happens in your browser and nothing you enter is stored or sent.
Frequently asked questions
How do I calculate 20% off a price?
Multiply the price by 0.8. For 45: 45 × 0.8 = 36. You save 45 − 36 = 9.
Is 30% off then 20% off the same as 50% off?
No. It equals 44% off: 1 − (0.7 × 0.8) = 0.44. The second discount applies to a smaller price.
Should I include VAT?
In countries where displayed prices already include VAT, such as the UK and most of Europe, leave the tax field empty. Use it where tax is added at the till, as in most of the US.