Discount Calculator
Sale price and savings
Enter discounts, coupon, and optional tax
Result
Calculation summary
Enter values to see the result
Price comparison
Original price versus final price
Formula
final = max(0, original × (1 − d₁) × (1 − d₂) − coupon) × (1 + tax)
- Final price
- $80.00
- Total savings before tax
- $20.00
- Effective discount
- 20%
How to use this calculator
- 1Enter the original price and the first discount percentage.
- 2Optionally add a second sequential discount, a fixed coupon, and a tax rate.
- 3Calculate the final price and review total savings and the effective discount.
Formula
Final price = max(0, original × (1 − d₁) × (1 − d₂) − coupon) × (1 + tax rate)
Each percentage discount applies to the remaining price, then the coupon is subtracted and the entered tax rate is applied.
Calculation steps
- Apply the first percentage discount to the original price.
- Apply the second percentage discount to the remaining price rather than adding the rates.
- Subtract the coupon without allowing the subtotal to become negative.
- Apply the entered tax rate to the discounted subtotal.
Worked example
A 100 item with 20% off and then another 10% off costs 72 before tax, an effective discount of 28%, not 30%.
Assumptions
- Percentage discounts are applied sequentially in the displayed order.
- The fixed coupon is applied after percentage discounts and cannot reduce the subtotal below zero.
- Tax is applied after all discounts; actual tax treatment can vary by jurisdiction.
- Changing currency changes formatting only and does not convert amounts.
Sources
Frequently asked questions
Why are 20% off and another 10% off not 30% off?
The second 10% is calculated from the already reduced price, producing an effective discount of 28%.
What happens if the coupon is larger than the remaining price?
The coupon is capped at the remaining subtotal, so the price before tax does not become negative.
Does this calculator know local tax rules?
No. It applies only the rate and order entered. Eligibility, taxable bases, and rounding rules vary.
Does currency selection convert the price?
No. It changes formatting only.