Black Friday ROAS: give the bidding your break-even number

Black Friday is the week shoppers convert at rates no other week matches, and bidding algorithms reprice every auction by the hour. What they need from you is one number: break-even ROAS, one divided by your margin rate, which a discount raises from 2 at a 50% margin to 3.5 at 30% off. With that target for each discount tier, they buy new customers at a price you chose in advance. Left on October’s target, they will still post the best ROAS of the year, on a week that may not pay. Here is the calculation, what the platform figure leaves out, and the six settings we make before the 27th in the accounts we run.

How a discount moves your break-even ROAS

The margin in question is contribution margin: the share of the selling price left once the product, the shipping and the payment fees are paid. Take a product sold at €100 that costs €50 to make and deliver. The margin is 50%, break-even ROAS is 2, and a campaign running at 4 is comfortable.

Now take 30% off, the level at which Adobe expects electronics discounts to peak this season. The price drops to €70 and the costs stay at €50, since nobody told them about the promotion. Break-even ROAS is now 3.5, and the campaign at 4 that ran at twice its break-even in October clears by a hair.

• Full price: €100 selling price, €50 of costs, 50% margin, break-even ROAS of 2.
• At 30% off: €70 selling price, €50 of costs, 29% margin, break-even ROAS of 3.5.
• At 30% off, with 17% of orders returned: break-even ROAS of at least 4.2, if every return goes back on the shelf at no cost. The campaign at 4 is now below it.

The 17% is what US retailers expected to see come back from last year’s holiday sales, according to the National Retail Federation. In the EU, an online shopper has at least fourteen days to change their mind. The ad platform records the order on Friday. The parcel comes back in December, once the results have been presented.

France adds a detail: since 2022, a crossed-out price has to be the lowest price of the previous thirty days. So the discount comes off a real price, and straight out of the margin.

Why your best ROAS of the year counts sales you already had

Black Friday week is an expensive one to advertise in. Among the biggest Meta spenders on Lebesgue, the median brand paid 59% more per thousand impressions than in September last year. Its Meta-reported ROAS still rose 19%, because its conversion rate jumped 48%. Some of those buyers come from your email list, your abandoned carts and everyone who typed your brand name on Friday morning: people who had decided, and who met an ad on the way to the checkout.

The evidence is old and solid: in a field experiment at eBay, published in Econometrica in 2015, brand keyword ads showed no measurable short-term benefit. In 2025 Meta rolled out incremental attribution, a setting that optimises and reports on the conversions its models predict the ad caused. The stricter number now comes from the platform itself.

Across the accounts we run, sales also dip in the two weeks before Black Friday and again in early December: part of Friday’s revenue is November and December revenue, shifted onto Friday and sold for less.

How to set your target ROAS for Black Friday

Automation is the right tool for a four-day event where prices, stock and auctions change by the hour, and it is most of what we do in paid search. It steers toward whatever target it is given. The six settings below are that target.

1. Compute break-even ROAS for each discount tier, net of returns. One line per tier, as above, with your own margins and return rate. It takes an hour. If the margins themselves are a guess, start with tracking.
2. Set the promo target. For the days of the sale, raise target ROAS to that break-even plus the profit you intend to keep. Give brand search and deep-discount products their own campaigns and targets. Once the target is right, budgets can follow demand instead of a cap.
3. Tell Smart Bidding the conversion rate is about to jump. Google built seasonality adjustments for short events of one to seven days where you expect a major change in conversion rate. Smart Bidding already handles the usual seasonal rise, so use them when your sale goes well beyond it. Bids return to normal on their own afterwards.
4. Report on margin. With conversion tracking set up properly, conversions with cart data and the cost of goods in your Merchant Center feed, Google Ads reports gross profit as well as revenue. The discount then shows up in the report on Saturday, and no longer in the accounts in January.
5. Pay more for new customers. A discounted first order can be worth buying below break-even when the second order follows. Google’s New Customer Value setting bids higher for new customers than for existing ones, as far as your customer list lets Google tell them apart.
6. Keep a holdout, and read it on day 30. Google’s Conversion Lift supports Search and Performance Max in the accounts that have access. Failing that, keep one region or a tenth of your customer list out of paid retargeting. Compare after the returns window, on the margin you kept, and across 1 November to 31 December against last year, so sales that only changed date are counted once. Some of the people who never saw an ad will have bought anyway.

What Black Friday is for

With a break-even target for each discount tier, Black Friday is a customer acquisition event at a price you chose in advance, executed by algorithms that adjust faster than any team could. On October’s target, the same algorithms do exactly what they were asked, for buyers already on their way. If you would like your targets checked before the 27th, book a call. It is a short one.