Stacked Discount Calculator · 2026 edition
Compare up to three stores with stacked coupons. Edit the sample prices to separate what you pay from credit for a future purchase.
Calculation and conversion of the text and files you enter happen in your browser, and the tool does not send your original input or results to a server. For traffic related to visit statistics and ads, see the privacy policy.
How to use it
- Replace the sample basket prices in Store A and Store B. To include a third quote, enable Store C under Store settings & exchange rate.
- Choose percentage or fixed coupons. Expand each coupon’s conditions to set a cap, minimum spend and calculation basis. Move coupons up to change their order.
- Expand shipping, card and rewards to enter delivery charges, a free-shipping threshold, card statement discounts and future credit.
- Review the order table and store comparison. Rounding applies to every store. Copy the summary when you are ready.
Examples
The same coupons can differ by KRW 1,000
On a KRW 100,000 basket, 10% followed by KRW 10,000 off gives 90,000 − 10,000 = 80,000. The fixed coupon first gives 90,000 × 0.9 = 81,000. This example has no shipping, card credit or rewards.
- Input
100000 → 10% → 10000
- Result
KRW 80,000
Future credit does not pay today’s bill
A KRW 10,000 purchase with 10% rewards still costs KRW 10,000 today. Future credit is KRW 1,000; effective cost is KRW 9,000 if you eventually use all of it.
Details
Coupons run in the entered order. A percentage coupon uses either the original basket price or the balance immediately before that coupon. Its minimum spend is checked against that same basis. A fixed coupon subtracts a set amount, but still uses the selected basis for eligibility. Each discount is limited by its optional cap and the remaining merchandise balance. Coupons cannot make that balance negative.
By default, every discount is rounded down to whole Korean won. On a KRW 999 item, 10% is 99.9: the discount becomes 99 and the balance is 900. With nearest-won rounding, the discount becomes 100 and the balance is 899. Half-won ties round up. Enter amounts with up to two decimal places and percentages with up to four. Amounts are limited to one billion input-currency units and one trillion KRW after conversion.
Free shipping is checked against merchandise after coupons but before the card statement discount. Card discounts exclude shipping. Final payment subtracts the statement credit from the checkout charge; the amount shown at checkout can therefore be higher. The total discount rate measures merchandise savings relative to the original price, excluding both shipping and future rewards.
Percentage rewards use merchandise after coupons and card credit, excluding delivery charges. Fixed rewards are capped at that same merchandise balance. Rewards represent credit for a later purchase and are shown separately from payment. Effective cost assumes you use every reward unit at face value. Expiration, restrictions, excluded products and card eligibility requirements are not modeled.
For foreign purchases, enter the number of Korean won per unit of the input currency. All amounts, caps and thresholds are first converted to whole KRW with the chosen rounding rule. Coupon calculations then use those converted values. There is no live exchange-rate lookup, currency-conversion fee estimate, customs duty or import VAT calculation. The order table compares the current order, percentages first and fixed coupons first, retaining the order within each group. It does not search every possible permutation.
Frequently asked questions
What does a blank cap or threshold mean?
A blank cap means no cap. A blank free-shipping threshold means no free-shipping offer. A zero cap allows no discount, while a zero shipping threshold always qualifies. Missing required numbers or invalid inputs prevent a cheapest-store verdict.
Why can the cheapest payment differ from the lowest effective cost?
Future rewards may make one quote look cheaper over time, but they do not reduce the bill for this purchase. The table marks both measures separately and marks all tied stores.
Can I really change the coupon order at checkout?
That depends on the retailer. This is a comparison of entered conditions, not a check of coupon compatibility or retailer rules. Confirm the final checkout breakdown before ordering.
Can I compare a foreign quote with a Korean quote?
Yes. Enter every monetary amount for each store in that store’s currency and set its KRW-per-unit exchange rate. Leave the rate at 1 for KRW inputs. All results are in KRW; customs charges are separate.