Discount Calculator — Percent Off, Stacked, BOGO & Reverse

Real-world use cases

• Compare two Black Friday coupon stacks before you buy

  A jacket is $180. Store A offers a flat 40% off. Store B offers 30% off plus an extra 10% coupon and free shipping. They sound the same. Open the stacked mode, enter $180, add a 30% step then a 10% step: the running price reads $126 then $113.40 — that is 37% off, worse than Store A's clean 40% ($108). Steps: pick "Stacked discounts", type the original, add each discount in order, and read the final "you pay" against the other offer. Two minutes of math saves you from the coupon-math illusion that almost always favors the store.

• Work out the real Double 11 cart total with 满减 plus a coupon

  Your 618 / Double 11 cart is ¥760 and the shop runs 满 300 减 50, which stacks on every full ¥300. Open the spend-X-save-Y mode, enter ¥760 cart, 满 300, 减 50: it triggers twice (¥760 holds two full ¥300 blocks), dropping you to ¥660. Switch off "apply once" to let it stack, or leave it on if the shop caps the promo at one use. Then add your store coupon as a separate flat step in stacked mode if it applies after the threshold. Now you know whether adding one more item to clear the next ¥300 tier is actually worth it.

• Decide if "second item half price" beats a straight discount

  A skincare set is $48 each with a "second item 50% off" banner, but the same brand elsewhere lists a flat 22% off. Open the BOGO mode, unit $48, quantity 2, buy 1, get 1 at 50% off: you pay $72 for two, an effective $36 each — a 25% effective discount, which beats the 22% straight deal. Steps: enter the unit price and how many you'll buy, set the free-item discount to 50, and compare the effective unit price to the competing flat percentage.

• Back-solve the discount rate from a price tag

  A tag shows $59 crossed out and $39 in red, with no percentage printed. You want to know if "打几折" this really is for a quick group-chat brag. Open the reverse mode, enter original $59 and sale $39: it reports 33.9% off, which is about 打 6.6 折. Steps: pick "Reverse", type the two prices, and copy the result string straight into the chat. Works the other direction too — paste a friend's "打 7 折" claim by checking whether the prices line up.

• Price a markdown for your own shop and see the margin hit

  You sell a product at $120 and want to run a sale without giving away too much margin. Enter $120 as the original, try 25% off — you net $90 and the customer saves $30 — then try a 满 100 减 30 threshold instead, which only triggers once per order and protects you on lower-ticket items. Steps: model both promos with the same original price, read the "you pay" and "you save" side by side, and pick the structure that moves units without torching your margin.

Common pitfalls

• Adding stacked percentages instead of multiplying them. 30% off then 10% off is 37% off, not 40%. Always read the running price after each step rather than summing the numbers in your head.

• Applying tax before the discount. Tax should be calculated on the discounted price, not the original — taxing the pre-discount amount inflates the total on money you never spent. This tool always discounts first, then taxes.

• Assuming buy-2-get-1-free always means a third off. It only hits that rate when your quantity is a clean multiple of the group size; leftover items pay full price, so the effective discount on an odd quantity is smaller than it looks.

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