Every Black Friday the instinct is the same: go deeper than last year. 30% becomes 40%. One competitor posts 50% off and the whole plan wobbles. Going deeper is the one move that reliably loses money, and the math isn't close.
Here's the case for holding your discount, backed by what actually happened in 2025 and by 20 years of research nobody reads before November.
The math nobody runs before the sale
A discount doesn't cost you the discount. It costs you the margin the discount comes out of. At a 50% gross margin, a 30% discount means you have to sell 2.5x the units just to make the same gross profit you'd have made at full price. Not 30% more. 150% more.
| Your gross margin | 20% off | 30% off | 40% off |
|---|---|---|---|
| 50% | +67% units | +150% units | +400% units |
| 60% | +50% units | +100% units | +200% units |
| 70% | +40% units | +75% units | +133% units |
The formula is your discount divided by your margin minus the discount, so 25% off a 60% margin is 25 ÷ (60 − 25). Wayflyer's break-even tool puts it plainly: at 25% off you need to sell 71% more units just to stand still. And that's before the extra ad spend needed to drive the volume, plus shipping and payment fees. Contribution margin is a smaller number than gross margin, so the real hole is deeper than the table shows.
Going deeper stops working, then reverses
Depth has a ceiling, and past it the line bends the wrong way. Bain's soft-goods data found that moving from 20% off to 30% off added just 7% more sales, while moving from 50% off to 60% off cut sales by 3%. You give away more margin and sell less. That's 2021 data, so read it as the shape of the curve, not this year's exact figures.
The current numbers say the same thing. Across Klaviyo's brands, average BFCM discounts fell about three points year over year, from roughly 29% to 26.2%, and same-store sales still grew 11%. The brands offering the smallest discounts grew 14%, the best of any group. Cutting less didn't cost them the weekend. And it isn't only a margin story: shoppers are showing discount fatigue. One 2025 survey found 13% fewer shoppers called price "very important" than a year earlier. Past a point, deeper mostly buys deal-native shoppers who were going to hunt for a code anyway, not incremental revenue.
What the discount actually trains
A discount isn't a one-time cost. It resets what the customer thinks your product is worth. The research on this is old and consistent: frequent promotions lower a shopper's reference price and teach them to treat your regular price as a number to wait out.
You can see it in the behavior. 77% of shoppers say they delay purchases to wait for year-end sales. 38% say they'll only buy at 50% off or more. And the customers you acquire this way mostly don't stick: of the buyers a brand acquires on Black Friday, only 4% come back within a year, and 75% of the few who do come back wait for the next Black Friday to do it. You didn't buy a customer. You bought someone who now only shops your sales.
There's a second cost that shows up later. Unpredictable, always-on discounting is the number one reason shoppers say they abandon a retailer for good, ahead of poor product quality. Train people to distrust your price and some of them stop trusting the brand.
The one thing that changes the answer: who you discount to
Here's the nuance most "discounts are bad" takes miss. The strongest causal study on this ran deep-discount offers against a control across tens of thousands of customers and tracked them for two years. On existing customers, the deep discount was a net negative: they went on to buy 10.8% fewer units and paid about 11% less per item. On genuinely new prospects, the same deep discount was a net positive: they bought 21% more later on.
So the move isn't "discount" or "don't." It's segment the discount. Deep offers belong in front of cold prospects who need a reason to try you. Your existing list, the people already buying at full price, should see your shallowest offer or none at all. One sitewide 40% blasted to everyone hands your best margin to customers who would've paid anyway.
Better levers than depth
If the goal is a bigger order and not a cheaper one, structure beats depth.
Gift with purchase. A $34 gift costs you about $9 in COGS. A $34 discount costs you $34. The customer values them about the same. One vendor's data across 1.1M Shopify orders found gift-with-purchase orders netted $172.88 versus $115.65 for discounted orders, and pulled a higher share of first-time buyers. That's an app maker's own data, so weight it accordingly, but the margin logic stands on its own.
Free-shipping thresholds. 81% of shoppers say they'll add to their cart to hit free shipping. A threshold set just above your average order value lifts basket size without touching unit price. Our free-shipping threshold calculator finds the number that adds AOV without eating margin.
Tiered spend-more-save-more. "Spend $150, save 15" gives the customer a reason to build a bigger cart to earn the deal instead of stapling a discount onto the order they already had. The saving becomes something they work toward, not a gift at checkout.
Klaviyo's data backs the restraint: the 10-15% and 20-25% discount bands drove the most conversions and revenue in its set, not the deepest ones.
What actually wins the weekend
The brand that wins Black Friday isn't the one that discounted hardest. It's the one that still has margin on the orders it took and customers worth keeping in December. A record sales number is easy to hit with a deep enough cut. The hard part, and the profitable part, is what you have left on December 1. That's the 7 days after Black Friday, and the full picture is in Black Friday by the numbers.
Part of the complete Shopify Black Friday playbook.
Written by Andrew Zam, co-founder of Liquid Lemon, a Shopify / Shopify Plus design + development studio. Figures reflect Klaviyo, Bain, Ometria, Wayflyer, BCG, Deloitte, and published marketing research for 2021 through 2025; check the current sources before you plan.
