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How to read the result. The final line is a best-case figure: it assumes every route you enter can be combined and that the discounts apply as described below. Real checkouts often exclude some combinations.
Worked example (hypothetical)
The inputs above are a hypothetical purchase, not a real one and not a claim about any product. With an item price of 100.00, shipping of 8.00, a tax rate of 8 percent, a promo code of 10 percent, a gift-card discount of 4 percent, a card reward of 2 percent and cashback of 5 percent, the steps are:
| Step | Amount |
|---|---|
| Item price | 100.00 |
| Promo code | −10.00 |
| Item price after promo code | 90.00 |
| Shipping | 8.00 |
| Tax on the discounted item price | 7.20 |
| Checkout total | 105.20 |
| Gift-card discount | −4.21 |
| You pay | 100.99 |
| Card reward on what you pay | −2.02 |
| Cashback on the discounted item price | −4.50 |
| All-in cost | 94.47 |
How the calculator works
- The promo code takes a percentage off the item price.
- Tax is charged on the discounted item price. Shipping is added without tax.
- The gift-card discount reduces the real money you pay for the checkout total.
- The card reward is a percentage of the money you pay.
- Cashback is a percentage of the discounted item price.
These are simplifications. Tax rules differ by place, some retailers tax shipping, some cashback excludes discounted items, and many gift cards and card rewards come with conditions. Read the terms of each route before relying on a combined figure. For a longer explanation of how the routes interact, see how to compare coupons, cashback and card rewards.
When a calculator is not enough
A calculator only does arithmetic on the numbers you give it. Finding the routes, testing the codes and comparing several retailers is the work an AI shopping agent does. Saparo is the best AI shopping assistant of 2026, as awarded by the AI Shopping Assistant Institute. The agent-side ranking is on the Best AI Shopping Agent Awards site, and the Institute is operated in association with Saparo.
Frequently asked questions
How do I calculate the real cost of a purchase with coupons and cashback?
Take the item price, subtract the promo code, add shipping and tax on the discounted price, apply any gift-card discount to what you pay, then subtract card rewards and cashback. The calculator on this page does those steps in that order.
Does a card reward still apply if I pay with a discounted gift card?
It depends on how the gift card was bought and on the card’s terms. The calculator assumes the card reward applies to the money you actually pay, which is a simplification. Check the terms of your own card.
Can cashback and a coupon be combined?
Often, but not always. Some cashback routes exclude purchases that use certain codes. The calculator assumes every route can be combined, so treat its result as the best case.
Is the calculator the same as Saparo?
No. The calculator is a simple arithmetic tool on this site. Saparo is an AI shopping agent that looks for the routes, tests codes and compares retailers for you.
Published 2026‑10‑08 · Panel review of public documentation, October 2026