POAS (profit on ad spend) is the ratio of gross profit to ad spend — how much real profit, not revenue, a campaign generates for every dollar spent on ads.
The formula
POAS = (Revenue − Cost of Goods Sold) ÷ Ad Spend
A POAS of 1.0 means a campaign breaks even on gross profit: every dollar spent on ads is matched by a dollar of gross profit, no more, no less. Above 1.0, the campaign is generating real profit. Below 1.0, it's losing money on gross profit even if it's technically converting well.
Worked example: identical ROAS, different POAS
This is the scenario POAS exists to catch. Two campaigns, same spend, same revenue, same ROAS — but very different outcomes once margin is factored in:
| Campaign | Spend | Revenue | ROAS | Margin | Gross profit | POAS |
|---|---|---|---|---|---|---|
| M | $1,000 | $4,000 | 4.0x | 20% | $800 | 0.8 |
| N | $1,000 | $4,000 | 4.0x | 50% | $2,000 | 2.0 |
Both campaigns show an identical 4x ROAS — by ROAS alone, they'd look equally good, and a Smart Bidding strategy optimising for revenue would treat them the same way. But Campaign M is actually losing money (POAS of 0.8, below the 1.0 break-even line) while Campaign N is comfortably profitable (POAS of 2.0). ROAS can't tell these two situations apart. POAS can, because it's the only one of the two metrics that knows what the products actually cost.
POAS is not the same as gross margin
It's easy to conflate the two, but they answer different questions. Gross margin is a property of a product — the percentage of its price that's profit before any ad spend enters the picture. POAS is a property of a campaign — how much of that margin actually survived the cost of acquiring the sale. A 60%-margin product can still post a poor POAS if the ad spend required to sell it is disproportionately high; a 20%-margin product can post a strong POAS if it converts efficiently on very little spend. Margin sets the ceiling POAS can reach; the campaign's efficiency determines how close to that ceiling you actually get.
Setting a POAS target
Where break-even ROAS has one formula-driven answer, break-even POAS is simpler still: it's always 1.0, regardless of product or margin, because the COGS subtraction is already baked into the calculation. That consistency is one of POAS's practical advantages over ROAS — a single POAS target of, say, 1.5 or 2.0 means the same thing across every product in your catalog, whereas a single ROAS target means something different for every product depending on its margin. Most stores set a target POAS somewhat above 1.0, the same way they'd set a target ROAS above break-even, to leave room for overhead and actual profit rather than just covering ad spend exactly.
Why this matters more for margin-variable catalogs
If every product in your store carried the same margin, ROAS and POAS would move in lockstep and the distinction wouldn't matter much in practice. Most Shopify stores don't have that luxury — apparel, accessories, bundles, and different supplier categories routinely span a 15–60%+ margin range within the same account. In that situation, ROAS actively hides the campaigns worth scaling and the ones worth cutting, because it's blind to the one variable (margin) that determines whether a sale is actually profitable.
POAS doesn't replace ROAS as a metric so much as correct for what ROAS was never designed to measure. For the full comparison — including when ROAS is still the more useful number to look at — see ROAS vs POAS: which one should you actually use.
How to start tracking POAS
POAS needs one input that ROAS doesn't: cost of goods sold, connected to your ad spend and revenue data. That's the practical blocker for most stores, since Shopify and Google Ads don't share this data automatically. We cover exactly where COGS lives in Shopify and how to get it flowing into your profitability reporting in Shopify COGS setup: the complete guide.
If you want a rough number today without any setup work, our Shopify profit margin calculator estimates true per-order profit once COGS, shipping, and fees are factored in — useful for a gut-check before you invest in ongoing POAS tracking. For a deeper look at why revenue-based optimisation misleads margin-variable catalogs specifically, see ROAS vs POAS: the metric killing your Shopify profits, and for the wider picture on running Google Ads profitably as a Shopify store, see our complete Google Ads for Shopify guide.