Discount Calculator
Work out the sale price and how much you save, including stacked discounts and sales tax.
Runs in your browser — your data never leaves your device.
About the Discount Calculator
Shopping in a sale? Enter the original price and the discount to see exactly what you will pay and how much you save. You can also handle "extra 10% off" deals and add sales tax or GST to see the final amount at the till.
The effective discount tells you the real percentage you save — handy because 20% + 10% is not the same as 30% off.
How to use the Discount Calculator
- Choose whether the discount is a percentage or a fixed amount.
- Enter the original price and the discount.
- Optionally add an extra discount (applied after the first one) and a sales tax / GST rate.
- Press Calculate to see the final price, your savings and a full breakdown.
Formula
- Discount amount = Price × Discount% ÷ 100
- Price after discount = Price − Discount amount
- Extra discount = Price after discount × Extra% ÷ 100
- Tax = Discounted price × Tax% ÷ 100
- Effective discount = Total saved ÷ Original price × 100
Examples
- 2,500 with 20% off → discount 500, you pay 2,000.
- 4,000 with 20% + extra 10% off → 4,000 − 800 = 3,200, then 3,200 − 320 = 2,880. Effective discount: 28%, not 30%.
- 1,000 with 15% off plus 18% GST → 850 + 153 = 1,003.
Frequently asked questions
Is 20% + 10% off the same as 30% off?
No. The extra 10% is taken from the already-reduced price, so the total saving is 28%. Enter both in the calculator to see the exact effective discount.
How do I calculate the original price from a sale price?
Divide the sale price by (1 − discount ÷ 100). For example, if an item costs 1,600 after 20% off, the original price was 1,600 ÷ 0.8 = 2,000.
Is tax calculated before or after the discount?
In most shops tax is charged on the discounted price, which is how this calculator works. Check your local rules if you are unsure.