Shopping Discount Calculator
Apply two sequential percentage discounts, an order coupon, quantity, and entered sales-tax rate to see final price and savings.
Interactive calculator · Method SHOPPING_DISCOUNT-1.1 · Last reviewed: 2026-11-04
Enter your scenario
Results update as valid inputs change. Correct any highlighted field before relying on the answer.
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
Sequential percentage discounts and the fixed coupon reduce $120.00 to $71.00 before the entered sales tax.
How to use the calculator
Combine sequential percentage discounts with a capped order coupon. Enter a whole-cent USD price per item, whole quantity, two percentage discounts, a whole-cent order coupon and an explicit tax percentage. The coupon applies after the discounted item price is rounded and multiplied by quantity.
What the result means
The model rounds once per discounted item before multiplying quantity, then rounds tax once on the post-coupon subtotal. Two percentage factors apply sequentially; they are not added. The effective pre-tax discount includes the coupon and is unavailable when original subtotal is zero.
Formula and units
Discounted item = half-up cents(price × (1 − first%/100) × (1 − second%/100)). Discount subtotal = rounded item × quantity. Coupon applied = minimum(entered coupon, discount subtotal). Taxable subtotal = discount subtotal − coupon applied. Entered tax = half-up cents(taxable subtotal × tax%/100). Total adds this tax. Savings compare original subtotal with taxable subtotal.
Worked examples
Original price per item: 120 USD per item; Quantity: 1 items: Original price per item: 120 USD per item; Quantity: 1 items; First discount: 25 %; Second discount: 10 %; Fixed order coupon: 10 USD; Sales tax rate: 8.25 %.
Example result: Final total: $76.86; Price per item after percent discounts: $81.00; Savings before tax: $49.00; Coupon applied: $10.00; Estimated sales tax: $5.86; Effective pre-tax discount: 40.83%.
Original price per item: 180 USD per item; Quantity: 2 items: Original price per item: 180 USD per item; Quantity: 2 items; First discount: 37.5 %; Second discount: 10 %; Fixed order coupon: 10 USD; Sales tax rate: 8.25 %.
Example result: Final total: $208.38; Price per item after percent discounts: $101.25; Savings before tax: $167.50; Coupon applied: $10.00; Estimated sales tax: $15.88; Effective pre-tax discount: 46.53%.
Limitations and common mistakes
Store coupon exclusions, order-level rounding and tax treatment can differ. The entered tax rate is applied to the modeled post-coupon subtotal; no jurisdiction or tax eligibility is inferred. Exact whole-cent totals are retained for large supported quantities.
Do not subtract an uncapped coupon below zero, apply the second discount to the original price again, or compare a tax-inclusive total with a pre-tax savings percentage.
Sources and assumptions
The formula is arithmetic; store-specific discount order, coupon exclusions, and tax treatment can differ.
Method SHOPPING_DISCOUNT-1.1; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.