Every month you pay Meta and Google to send people to your store. Most of them leave without buying, and many of the people who do buy never come back. How much you can spend to win the next customer depends almost entirely on what happens after that first visit.

We call it your allowed cost per customer, or allowed CAC, and it sets the ceiling on what you can bid in the ad auction. Brands that raise the ceiling can keep buying traffic when costs go up, while brands that don't are forced to stop.

Start with what one order is worth

Revenue per order is the wrong starting point, because most of it is not yours to spend. Take your average order value and subtract what the order costs you to fulfil: the product itself, shipping, payment fees and returns. What is left is the contribution margin per order.

An example with round numbers: a store with an average order of €80 and a contribution margin of 40% keeps €32 per order. That €32 is the most it can pay to get one order without losing money.

The same logic gives you your break-even ROAS. Divide 1 by your contribution margin. At 40% margin, break-even ROAS is 2.5. A campaign reporting a ROAS of 2 looks fine in Ads Manager and loses money on every first order.

Then look at what one customer is worth

A customer who orders once is worth one contribution margin. A customer who orders again is worth more, and that is where the ceiling starts to move.

Back to the €80 store. If the average customer places 2.5 orders in their first year, a customer is worth €80 in contribution margin over that year, two and a half times the first order. The store can now afford to pay up to €80 to acquire a customer and still break even within twelve months, where the first-order view said €32.

If you want a buffer, you can aim for a ratio such as 3:1 between what a customer is worth and what it cost to acquire. At 3:1 the store's target becomes about €27 per customer. Judged on the first order alone, the same rule would allow less than €11. Raise repeat purchases and the target rises with them.

Why this decides the auction

Picture two stores that sell an identical product at an identical price. In the first, a customer is worth €32. In the second, follow-up orders lift that to €80. The second store can bid more than twice as much for the same click and still make money, and when ad costs rise it can keep spending while the first store has to pull back.

The products are identical, and the ad accounts may be too. The difference is what each store does with a customer after the first order.

What raises the ceiling

Two things move what a customer is worth, and both happen after the ad has done its job.

Capturing the visitors who don't buy. Most paid visitors leave without buying and without leaving an email address, which means you paid for them and can't reach them again. A signup form that converts well turns some of them into subscribers you can sell to later without paying for the click a second time. In one client account, raising the signup rate from 1.5% to 19% grew welcome flow revenue almost thirteen times within three months.

Bringing first-time buyers back. Post-purchase flows, replenishment reminders, win-back flows and regular campaigns are what turn one order into two or three. Every extra order raises customer value, and with it the price you can pay in the auction.

Work it out on your own numbers

You need four figures, all of which you already have:

1. Average order value, from your shop platform.

2. Contribution margin as a percentage of the order, after product cost, shipping, payment fees and returns.

3. Average number of orders per customer in their first 12 months.

4. Your current cost per new customer, from your ad accounts.

Multiply the first three to get what a customer is worth in contribution margin over a year. Divide it by your payback target, for example 3, and compare the result with the fourth number. If your current cost per customer is close to or above that line, the fix lies in raising what each customer is worth, because more traffic at the same value only repeats the problem at a larger scale.

Where Markeity comes in

This is the number we work on. We build the Klaviyo setup that captures more of the traffic you already paid for and brings buyers back for the next order, so your ad account can bid higher without losing money. If you want to see what your own numbers say, book a free 15-minute call and bring your order value and margin. To see how this plays out when you scale ad spend, read Why ROAS falls when you scale Meta ads.