Tracking the same set of KPIs across a Search campaign, a Shopping campaign, and a Performance Max campaign is the most common mistake we see in Shopify Google Ads accounts. These three campaign types don’t share the same objective, the same level of control, or the same visibility — the metrics worth watching therefore differ structurally between them.

This article breaks down the KPIs that matter by campaign type, and the attribution traps specific to Performance Max, the campaign type most Shopify stores now run and the one most often misread.

KPIs that apply across all campaign types

Before getting into type-specific detail, three metrics read the same way everywhere:

ROAS — revenue divided by spend. As with Meta, always compare against your breakeven ROAS (1 ÷ gross margin), never in isolation. Google Ads figures rest on its own attribution window (30 days by default, configurable), which differs from GA4’s — we cover this mechanism in our attribution guide.

CPA — cost per acquisition, always compared against the average order value of the products that campaign targets.

Impression share — the percentage of times your ads could have shown and actually did. A low impression share on a high-ROAS Search campaign signals insufficient budget to capture available demand — often a sign that increasing budget would increase revenue without degrading profitability.

Search: the intent KPIs

A Search campaign targets active queries — the user is already articulating a need. The KPIs worth watching reflect that intent:

Conversion rate by ad group, not just at campaign level: an uneven conversion rate across ad groups points to a mismatch between the searched keyword and the landing page.

Quality Score — Google’s quality rating (ad relevance, landing page, expected CTR) directly influences CPC. A low Quality Score inflates cost per click at equal position; it’s often the hidden cause behind a CPA that climbs without apparent explanation.

Actual search terms (the Search terms report) — essential for excluding off-topic queries that consume budget without converting, particularly on broad or phrase match keywords.

Shopping: the product KPIs

Shopping campaigns display your products directly (image, price, title) — steering happens at the product level, not the keyword level.

ROAS by product — Shopping exposes this granularity natively, unlike Search. A product with a ROAS far below account average drags the whole thing down; excluding it or adjusting its bid individually often lifts overall performance without touching total budget.

Click-through rate by product category — helps spot categories that attract attention in the shelf (good CTR) but convert poorly, often signaling a pricing or stock availability issue.

Product feed quality (in Merchant Center, not Google Ads directly) — optimized titles and descriptions, compliant images, prices synced in real time with Shopify. A poor-quality feed limits distribution before bidding even enters the picture.

Performance Max: limited KPIs, and why

PMax automates delivery across Google’s entire inventory (Search, Shopping, Display, YouTube, Gmail, Maps) through a single bidding algorithm, with a tradeoff Google states openly: channel-by-channel visibility is deliberately reduced.

What you can track: overall campaign ROAS, conversions, and — since recent interface updates — an indicative channel report (Search, Display, YouTube…) intended as information rather than fine-grained steering.

What you can’t track precisely: exact budget allocation by channel, the search terms that triggered a conversion (a far more limited report than Search), and product-by-product detail at the same granularity as classic Shopping.

The attribution trap to know about: PMax can cannibalize traffic that would have converted anyway through classic Search or organic (a customer who already knew your brand and would have clicked your Search link or your free Google Business listing sometimes gets intercepted by a PMax ad instead). PMax’s isolated ROAS can therefore look excellent while partly representing sales that would have happened without it. The most reliable signal for settling this: watch account-level ROAS (Search + Shopping + PMax combined) before and after activating or increasing PMax budget, rather than PMax ROAS in isolation.

Building a dashboard for multi-campaign accounts

Stacking every KPI from Search, Shopping and PMax onto a single dashboard without distinction produces confusion. The structure that works: a summary page anchored on account-level ROAS, then a section per campaign type with its own relevant KPIs — exactly the structuring logic we detail in our Looker Studio dashboard guide.

FAQ

Should I favor Shopping or Performance Max for a Shopify store? PMax has largely replaced classic Shopping in Google’s recommendations since its rollout, but some accounts get better control (and sometimes better measurable ROAS) by keeping classic Shopping running in parallel, particularly on a small catalog where manual product-level management remains feasible.

Why does my PMax ROAS look better than my Search campaigns? Often because PMax captures traffic that would have converted through Search or organic anyway — see the attribution trap above. Always compare the evolution of account-level ROAS, not isolated ROAS by campaign type.

Does Quality Score affect Shopping and PMax the way it does Search? Quality Score in the strict sense (with a visible score) exists only for Search. On Shopping and PMax, product feed quality and landing page relevance play an equivalent role but without a displayed score.

Want a dashboard that centralizes Search, Shopping and PMax ROAS alongside your real Shopify margin? Check out our Shopify Dashboards offer or book a free 30-minute call.