Stack multiple discounts (promo + sale + loyalty + cashback) with tax and see how reordering changes the final price.
Most calculators handle one discount. This one stacks them — promo code, sitewide sale, loyalty, cashback, and tax — in the exact order they apply. Order matters: a 20% off then 10% off is not the same as flat $20 then 10%, and tax-before vs tax-after can swing the total by several dollars. The waterfall view shows every step, and the order optimizer brute-forces all permutations to find the lowest legal final price.
If you see "20% off" plus "extra 10% off at checkout," your brain wants to call it 30% off. It is not. The second 10% is applied to a price that has already been reduced 20%, so the real saving is 28%, not 30%. Add a flat $5 cashback after tax and the math gets messier still. Stacking is a sequence of operations, and each step changes the base for the next one.
In the United States, sales tax is almost always charged on the discounted subtotal, so applying coupons first lowers your tax bill too. In VAT and GST jurisdictions like the EU, UAE, and India, the rules vary: manufacturer rebates are often taxed on the gross price while retailer discounts reduce the taxable base. The calculator lets you toggle between both so you can verify a receipt or compare offers fairly.
The optimizer tests every possible ordering of your discounts (up to six rows) and reports the arrangement that produces the lowest legal final price. For pure-percentage stacks the order does not matter and you will see "already optimal." Once a flat-amount coupon enters the mix, ordering matters: applying the flat coupon first wastes part of the percentage discounts, while applying it last maximizes them.
Yes — for percentage discounts, order does not matter (20% then 10% equals 10% then 20%). But mixing percentages with flat amounts changes everything. A flat $20 off applied before a 20% discount also reduces the percentage savings, while applying it after preserves the full percentage off.
In most US states tax is charged on the discounted price (after), which is better for the buyer. VAT/GST regimes (EU, UAE, India) typically calculate tax on the gross or invoiced price depending on the discount type. The calculator shows both so you can sanity-check what the retailer is doing.
Cashback is applied last, after tax, because it is reimbursed to you separately rather than reducing the price the merchant charges. The calculator treats it as a final reduction to your effective out-of-pocket cost.
It is the total amount saved divided by the original price, expressed as a percentage. Stacking a 20% + 10% discount does not give 30% off — it gives 28% off, because the second discount is applied to an already-reduced price.
Yes — most stores limit you to one promo code per order, and many exclude sale items from coupons. Always read the fine print. This calculator assumes every discount you enter is allowed; use it to evaluate offers, not to dispute a checkout.
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