The break-even ROAS formula, and the retention trick that lowers it

A 3.0 ROAS can be great or a slow way to go broke. It depends entirely on your margins. The break-even ROAS formula tells you the line between the two, and once you add retention into the picture, it also tells you how much harder you can bid than a competitor with no email program.

The break-even ROAS formula

This is the same structure Shopify uses in its own break-even ROAS guide. At break-even ROAS, every dollar of ad spend brings back exactly enough revenue to cover the product, shipping, fees and the ad itself. Above it you make money. Below it, every sale costs you.

Quick reference table

Notice how fast it climbs as margins thin. Going from 40% to 30% margin pushes the line from 2.5 to 3.33. That's why cutting costs per order is often a faster win than “better ads.”

Write your break-even number on a sticky note and keep it next to your ads dashboard. Every time you look at a campaign, the only question that matters is: is this above my line, and by how much? Everything else (CTR, CPM, “great engagement”) is a means to that end.

Which costs go in (and which stay out)

Include anything that scales with each order:

1. Cost of goods: the landed cost of the product.
2. Shipping and packaging, including what you subsidise on “free shipping.”
3. Payment processing fees.
4. Pick and pack / 3PL fees.
5. Returns allowance, if returns are a real part of your business, such as apparel.
6. Average discount, if most orders use a code. Or calculate on net revenue after discounts.

Leave out fixed costs like rent, salaries and software. Shopify's guide makes the same split: fixed costs belong in your profit and loss, not in the per-order break-even.

Worked example: one product, three ROAS numbers

The target ROAS formula

Set a target profit margin per order (say 10–15%), then check campaigns against the target, not the break-even. Break-even is the floor. Target is the bar.

The retention trick: why email lowers your real break-even

Here's what most ROAS guides leave out. A first-order break-even treats every customer like they'll never come back. For most stores that isn't true, and it doesn't have to be.

A study of 1,500+ Shopify stores by Little Stream Software found an average repeat purchase rate of 25%, a median of 22.5%, and 1.8 orders per customer across the full data. Every point you add to that through email and SMS raises what a new customer is worth, and so lowers the ROAS you need on the first order.

And retention revenue is cheap to produce. Klaviyo's 2026 benchmarks show email flows earn nearly 41% of email revenue from just 5.3% of sends. Once the flows are built, they keep running for every new customer.

How to use this without fooling yourself

1. Use real repeat data, not a hoped-for number. Measure it in the repeat purchase rate calculator.
2. Pick a payback window (6 or 12 months) and only count repeat profit that lands inside it.
3. Count only contribution from repeat orders, not revenue.
4. Re-check every quarter. If repeat rate drops, your lifetime break-even goes back up.

Then compare lifetime value to acquisition cost in the LTV:CAC ratio calculator, and check the result against what a good LTV to CAC ratio for DTC brands looks like on a margin basis.

5 ways to lower your break-even ROAS this month

1. Raise AOV. Bundles and a free-shipping threshold just above your current AOV spread fixed per-order costs over more revenue. Model it in the AOV calculator, and see my 9 tricks for how to increase AOV with email marketing.
2. Renegotiate shipping and packaging. A dollar off shipping on a $75 order adds 1.3 points of margin.
3. Stop sitewide discounting. Codes come straight out of contribution. Keep incentives for flows like cart and win-back, behind “first-time buyer” or “high value” splits.
4. Fix returns. Better size guides and product pages reduce the returns allowance.
5. Build the second order. Post-purchase, replenishment and win-back flows. See how to increase repeat purchase rate and the win-back email flow.

One store, many break-even ROAS numbers

A single store-wide break-even hides a lot. Your hero product might run at a 60% margin while a heavy, cheap accessory runs at 25%. Put both in the same campaign and a “good” blended ROAS can be quietly losing money on half the orders.

• Calculate break-even per product or collection for anything you advertise on its own.
• Group campaigns by margin band so each one has a clear target.
• Watch the order mix. If a promotion shifts sales toward low-margin items, blended ROAS can hold steady while profit falls.

This is also where email helps: you can use flows to steer repeat buyers toward high-margin products, which raises average contribution on the orders that come back without any ad spend at all.

4 mistakes that make break-even ROAS wrong

1. Using product cost only. Leaving out shipping and fees makes break-even look lower than it is, so you scale campaigns that lose money.
2. Using gross sales instead of net. Discounts and refunds come off revenue before you calculate margin.
3. Mixing fixed costs in. Adding rent and salaries per order makes the number swing with volume and hard to act on. Keep those in your P&L.
4. Trusting platform ROAS alone. Attributed revenue overlaps across platforms. Check it against MER and Shopify's own reports.

Not sure what your margin is? Work it out in the ecommerce profit margin calculator first, then bring the number back here.

ROAS, MER and the attribution trap

Platform ROAS is attributed, and platforms overlap. Meta, Google and Klaviyo can all claim the same order, as Shopify's guide also warns. Two habits help:

• Track MER (total revenue ÷ total marketing spend) alongside platform ROAS, as a reality check.
• Track new-customer revenue separately. Ads should be judged on new customers; email should be judged on bringing them back.

Run your basic ROAS in the ROAS calculator, then compare it to your break-even and target numbers. If you're above target, scale. Between break-even and target, optimise. Below break-even, pause and fix margin or retention first.

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