BFCM Margin Math: Offers That Survive

Every store plans a Black Friday offer. Few write down what each candidate earns per order before choosing. This post does that for four common offers (30 percent off, a gift tier, buy one get one at half price, and free shipping) on one invented store, so the BFCM margin of each is visible in the same units. There are no benchmarks here, no "stores that do X see Y". Every number comes from an assumption in the first table, which you can replace with your own.

For the calendar: the federal holiday list shows Thanksgiving falling on Nov. 26, 2026, so Black Friday is Nov. 27 and Cyber Monday is Nov. 30. Shopify reported in an SEC filing dated Dec. 2, 2025 that its merchants sold a record 14.6 billion dollars over the 2025 Black Friday through Cyber Monday weekend, with an average cart price of 114.70 dollars (Shopify labels its figures approximate). That context is why the offer decision matters: a lot of volume is at stake in that week. It says nothing about which offer is right for you, and the math below does not borrow from it.

One store, four offers, same traffic

The store is invented and every input is an assumption.

The four offers, each applied to that same store:

• A. 30 percent off everything. The shopper pays 56 dollars for the same two units.
• B. Gift tier at 100 dollars. Spend 100 dollars, get a gift that costs the store 6 dollars landed. Assume the shopper who takes it stretches from 80 to 100 dollars.
• C. Buy one, get the second at 50 percent off. The pair costs the shopper 60 dollars for the same two units.
• D. Free shipping on every order. The store absorbs the 8 dollars the shopper paid before.

Profit per order

Offer A cuts profit per order by more than half. Offer B earns more per order than a normal week, but only because we assumed the shopper adds 20 dollars of products to qualify. If the shopper was going to spend 100 dollars anyway, the gift is a straight 6 dollar loss on that order. Offers C and D sit in between.

The volume each offer needs

The test that matters is how many orders each offer needs in order to make the same profit as the normal week, 12,414 dollars.

To break even, a 30 percent sitewide discount must more than double your orders from the same traffic. Free shipping needs about one in four more orders. The gift tier needs fewer orders than normal, but only if the shoppers who qualify really spend the extra 20 dollars, which is the thing to test and not assume. For the general method, see Break-Even Discount: Extra Volume You Need.

Fees and returns

The payment fee shrinks with the order, so a discount makes it a larger share of what is left: 2.62 dollars is 6.3 percent of the 41.38 dollar profit in a normal week, and 1.92 dollars is 10.6 percent of the 18.08 dollars left under offer A. Change the fee assumption and the table moves a little: each half point of fee changes a normal order by 0.40 dollars.

Returns need their own assumption. Suppose 8 percent of orders come back for a full refund, the goods can be resold, the payment fee is not refunded, and the store pays no return label. Then a returned order loses its profit and costs the fee, and every offer above scales almost the same way: offer A's required multiple moves from 2.29 to 2.30. The returns that change the ranking are the ones you pay to ship back, and discounted orders have less margin to absorb them, so put your real return-label cost into the model before you trust any row.

Which offer survives at 35, 55 and 70 percent gross margin

Product cost scales with margin. The multiples below are the orders needed as a multiple of normal orders, using the same assumptions and only changing the gross margin on the 80 dollar order.

At 35 percent, 30 percent off leaves 2.08 dollars per order, so you would need 12 times your normal orders to match the week. Even buy one get one at half price needs more than four times. At 70 percent the same offers need under two times, which is still a lot of added traffic, but within the range of a well-promoted week. Free shipping is less sensitive to margin than offers A and C because its cost is a flat 8 dollars while the discounts scale with revenue.

Buy one get one free is not in the table because it is worse than the half price version at every margin shown: on this store a free second unit leaves 2.54 dollars per order at 55 percent and loses 13.46 dollars at 35 percent. Our post on BOGO vs 50% Off the Second Item has the pair margin by offer type.

What the table does and does not tell you

It says which offers have room, not which will work. It does not predict how many extra orders any of them brings, and it treats the offer as applying to every order. In practice a gift tier or a free shipping line at a threshold only touches the orders above it, as discussed in Free Shipping Threshold: The Formula, and a tier can be set just above your normal order so the qualifying share is small. The plan for the whole week, including dates and sequencing, is in Black Friday Cyber Monday Offer Plan (US).

Building the winner

At margins near 55 percent, the model favors a gift tier or a threshold-based offer over sitewide discounting, because it spends money only where a shopper adds to the order. If that is your case, the Spend X, get a gift template in Freebies Engine by Log Studio Lab is described as "Shoppers who reach a cart value get a gift added automatically." Set the cart value above your usual order, cap the gift stock, and set the end time for the offer before the week starts. The step-by-step admin version is in Free Gift With Purchase on Shopify: Setup.