Break-even ROAS and maximum CPC: how much you can really pay per click

Why a „good ROAS” doesn't exist — and what replaces it

There is no universal „good ROAS” — there is only your profitability threshold, set by your margin. A ROAS of 3.0 is excellent at a 20% margin and a disaster at 60%, because in the first case you make money and in the second you hand your profit to a competitor who bids more aggressively. So the question „what ROAS is good” is the wrong one. The right one is: what is my break-even ROAS, and how much can I therefore pay for a single click.

Most guides stop at the formula break-even ROAS = 1 / margin and consider the topic closed. That is only half the journey. The ad platform bids on your behalf at the level of cost per click and cost per conversion — so until you translate the profitability threshold into a maximum CPA and CPC, you are setting targets by feel. This article shows the full path: from margin, through break-even ROAS, to the concrete amount you can afford to spend on a click.

How to calculate your break-even ROAS from margin

Break-even ROAS is one divided by your gross margin: at a 40% margin it is 1 / 0.40 = 2.5, and at 25% it is 4.0. It is the return on ad spend at which you break even — every penny above it is profit, every penny below it is subsidizing the sale. Margin here means margin on the product (price minus cost of goods), not markup or net margin after all costs — we will come back to that shortly, because it is the most common source of error.

The threshold itself is abstract, though, until you translate it into money per order. Your maximum cost to acquire an order (CPA) at break-even is simply your gross profit on one order: margin times average order value (AOV). The table below shows this for a 250 PLN basket — the most important column is the last one, which most guides leave out.

Notice how strongly margin changes the game: a store with a 60% margin can pay four times more per click than one at 15% — and in the same Google Ads auction, one of them will always outbid the other. If your real break-even ROAS is higher than the rates at which you buy clicks, the channel isn't „not working” — you are simply bidding above your threshold.

Why your real threshold is higher than you think

Your real break-even ROAS is almost always higher than the one from gross margin, because the true cost of an order isn't just the cost of goods. Returns, shipping and packaging, payment and platform fees, and for some sellers VAT — all of it eats into margin before any profit is left. Calculating the threshold from „bare” gross margin systematically overstates how much you can afford per click, which is why a campaign that looked profitable on paper shows a loss after a month.

The conclusion is uncomfortable but healthy: before you optimize campaigns, calculate your contribution margin — what is left of an order after all variable costs. That, not the margin from your price list, sets your real threshold. The difference between 2.00 PLN and 1.40 PLN per click decides whether scaling the campaign adds profit or grows a loss.

From ROAS to bid: how much you can pay per click

You calculate the maximum cost per click in two steps: first the maximum cost per order (max CPA = contribution margin × AOV), then multiply it by the conversion rate (max CPC = max CPA × CVR). That is the whole equation missing from most ROAS guides — and the only one you actually set in the panel, because the auction plays out at the level of the bid per click, not per abstract „return”.

That number — 1.40 PLN — is your ceiling, not your target. At it you break even; to make money you must buy clicks cheaper or raise conversion and basket size. The biggest lever often isn't the bid but the conversion rate: if the same store lifted CVR from 2% to 3%, the maximum CPC rises from 1.40 PLN to 2.10 PLN, because an order now takes about 33 clicks instead of 50. That is why optimizing the site and the purchase path is often a cheaper route to a „higher bid” than bidding itself.

Translating the threshold to the panel: Target ROAS and Target CPA

In the panel you don't set „break-even” — you set a target that leaves you a profit, i.e. a bid safely below the threshold. If you want to keep half your gross profit, aim for a CPA equal to half the maximum: with a max CPA of 70 PLN, set a target of 35 PLN, which corresponds to a target ROAS of 250 / 35 ≈ 7.1 and a maximum CPC of about 0.70 PLN. The rule is simple: target ROAS = AOV / target CPA, and you choose the target CPA so it covers the threshold plus your intended profit.

In campaigns with automated bidding (Target ROAS / Target CPA on Google Ads and Meta Ads) you enter exactly these values — but the algorithm will only optimize toward as good a number as you give it. A target pulled from thin air (because „the competition has a ROAS of 4”) is worse than one calculated from your own margin, even if it looks more ambitious. Start from the threshold, add your profit margin, and only then hand control to the automation.

When you can pay more: LTV and repeat purchases

If a customer comes back and buys again, you can pay more for their first click than a single order implies — because you are acquiring not a transaction but a relationship. Counting the threshold from the first basket alone systematically underbids and hands the market to a competitor who looks at customer lifetime value (LTV). It is the most common reason a store with a good product „can't fit into” the auction: it counts the threshold on one order when it should count it on three.

Caution is warranted in the other direction, though: raise the bid based on real, data-confirmed repeat behavior, not wishful LTV from a slide deck. The safe approach is to calculate the threshold over a firm, short window (e.g. 90 days) and treat further purchases as a buffer, not an assumption. How much you can actually raise the budget also depends on how much is worth spending on the channel at all — we laid that out in our benchmark on how much to spend on Google Ads and Meta Ads.

The most common mistakes when calculating the profitability threshold

The costliest mistake is calculating the threshold from the panel's ROAS instead of from your own margin — because the panel gets revenue wrong in both directions. An attribution-inflated ROAS will tell you that you can afford a higher bid than you really can; it is the same mechanic we described with Performance Max and inflated ROAS and Advantage+. Below is a shortlist of the errors that most often skew the calculation.

• Gross instead of contribution margin — skipping returns, shipping, fees, and VAT overstates max CPC by as much as 30–40%.
• Threshold from the panel's ROAS — attribution inflates revenue, so the threshold comes out too optimistic; calculate from hard margin, not the panel number.
• One target ROAS for the whole account — with different SKU margins, the high-margin product subsidizes the low-margin one.
• Ignoring the conversion rate — without CVR you can't move from CPA to CPC; conversion, not the bid, is often the biggest lever.
• Counting only the first order despite real repeat behavior — you underbid and lose the auction to competitors who look at LTV.

The common denominator of these mistakes is the inputs: margin, AOV, and conversion must be true, or everything else is guesswork. That is why a trustworthy threshold starts with airtight measurement — without it, conversion rate and basket value get lost to consent prompts and cookie blocking. We unpacked this in our piece on server-side tracking, and we deliver the implementation as server-side tagging. If you'd rather have someone calculate these thresholds and build campaigns around them, that's the daily work of the marketing agency Zest.

FAQ: break-even ROAS and maximum CPC