Discount calculator — sale price and savings, with stacked discounts and tax.
Stacked discounts multiply, they do not add: 20% then 10% is a 28% total discount, not 30%, because the second discount applies to the already-discounted price.
Tax is added after all discounts, on the sale price.
Tip: to find the discount percentage from two prices, use (original − sale) ÷ original × 100. A $100 item on sale at $75 is a 25% discount.
sale price
How to use this tool
Type the full price before any discount. This discount calculator works out the sale price and exactly how much you save.
Type the discount — for example 25 for 25% off. The sale price, the amount saved and the effective discount percentage all update instantly.
Open Advanced options to add a second discount, applied to the already-discounted price. Remember: 20% then 10% is 28% off in total, not 30% — that is how to calculate discount percentage when offers stack.
Add a sales tax or VAT rate in Advanced options and the calculator gives the total you actually pay, with the tax amount shown separately.
Formula & worked example
Worked example: a $100 item at 25% off costs $100 × (1 − 0.25) = $75, so you save $25. With stacked discounts of 20% then 10%: $100 × 0.80 = $80, then $80 × 0.90 = $72 — saved $28, an effective discount of 28%, not 30%. Add 8% tax and the till total is $72 × 1.08 = $77.76. Going backwards, a $100 item on sale at $75 is ($100 − $75) ÷ $100 = 25% off.
Limitations — read this before you rely on it
This calculator applies percentage discounts to one price. It does not model fixed-amount coupons, buy-one-get-one offers, minimum-spend thresholds, or tax rules that differ by product or region. The till total assumes tax is charged on the discounted price, which is the usual rule but not universal.
Frequently asked questions
Subtract the sale price from the original price, divide by the original price and multiply by 100. For example, ($100 − $75) ÷ $100 × 100 = 25% off. To go the other way, sale price = original × (1 − discount %).
Each discount applies to the price left by the previous one, so they multiply rather than add. 20% then 10% on $100 gives $80 then $72 — a 28% total discount, not 30%. The bigger the discounts, the bigger the gap from simply adding them.
The headline sale price here is before tax. Add a tax rate in Advanced options and the calculator shows the tax amount and the total you pay at the till, since tax is normally charged on the discounted price.
The discount is the percentage (or amount) taken off; the sale price is what remains. On a $100 item at 25% off, the discount is 25% ($25) and the sale price is $75.
Yes: original price = sale price ÷ (1 − discount %). An item on sale at $75 with a 25% discount originally cost $75 ÷ 0.75 = $100. Use the same formula in reverse for any sale.