Custom labels strategy for Google Shopping on Shopify stores

Custom labels are five free attributes in your Google Merchant Center feed that let you group products by any value you define. For a Shopify store advertising on Google Shopping, this is the fastest way to control which products get budget and which do not. Without custom labels, every item in your feed competes for the same bid, whether it is a strong-margin best seller or a clearance item you are trying to clear from inventory.

This guide covers the core custom label strategies for Shopify merchants: margin segmentation, seasonality, sales performance, and how to apply each one inside Performance Max campaigns and standard Google Shopping campaigns.

What custom labels are and why Shopify merchants need them

A custom label is a field in your product feed. Google gives you five slots, numbered custom_label_0 through custom_label_4. Each slot holds one value per product. You define what each label represents and what values it can take.

Custom labels do not change which search queries your products match. Titles, descriptions, and product type attributes handle that. Custom labels exist for one purpose: to let you group products inside your Google Ads account and apply different bidding, budget, or reporting rules to each group.

For a Shopify store, this matters because your catalogue is rarely uniform. A store selling apparel might have summer stock, winter stock, strong-margin accessories, and lower basics all in the same feed. Without a way to separate them, Google's automated bidding treats a below-margin base product the same as a strong-margin best seller. Custom labels fix that by giving Performance Max and standard Shopping campaigns a signal to work with.

How to add custom labels to your Merchant Center feed

There are two common ways to add custom labels to a Shopify-connected feed.

The first is manual tagging inside Shopify, paired with a feed app that maps Shopify tags to Merchant Center custom label fields. You add a tag to a product, such as "premium-margin" or "clearance," and the app writes that tag into the correct custom_label field on sync.

The second is feed rules set directly in Merchant Center. Feed rules let you create a value based on criteria already present in your feed, such as price, product type, or inventory age, without touching your Shopify product data at all. This is useful when the criteria you want to segment by, like price ranges or margin bands, can be calculated from data you already have.

Whichever method you use, keep the definition of each custom label consistent. If custom_label_0 is set to represent margin on one product, it should represent margin across your entire catalogue. Mixing definitions across products breaks reporting and makes it hard to build reliable product groups later.

Custom labels let you subdivide products in your campaigns using values that you define, and you can have up to five, numbered zero to four. This structure works the same way whether your feed comes from Shopify, a supplemental feed, or a custom integration, which is what makes custom labels such a flexible tool for segmentation.

Segment product groups by margin

Margin is the most commercially useful way to segment a Shopify catalogue. A strong-margin product and a low-margin product can produce the same return on ad spend and still deliver very different profit. A 6x return on a product with a 15 percent margin is not the same business outcome as a 6x return on a product with a 60 percent margin.

To implement this, set one custom label to represent margin tier. Common values are high-margin, mid-margin, and low-margin, or you can use price ranges as a proxy if you do not have exact margin data synced to your feed.

Once the label is live, split your product groups in Google Ads by that custom label. Give high-margin products a higher target ROAS ceiling or more aggressive bids, since a lower return still generates more profit per sale. Give low-margin products a stricter target so you are not spending disproportionately to move products that barely cover their own ad cost.

Segment by seasonality with Summer, Winter, Spring and Fall labels

Seasonality is the classic custom label use case, and it is especially relevant for Shopify stores with rotating stock. Set a custom label to represent season, with values such as Summer, Winter, Spring, and Fall.

This lets you do two things. First, you can build campaigns or product groups around in-season stock and raise bids as the season approaches. Second, and just as important, you can reduce or exclude out-of-season products so they stop consuming budget once demand drops. A swimwear line does not need the same bid in November that it needed in June.

If your store carries year-round staples alongside seasonal items, add a value such as "evergreen" so those products are not accidentally grouped with seasonal stock and excluded at the wrong time.

Segment by Best Seller and clearance status

Sales performance is another high-value custom label. Tag your top performers with a Top Seller value and give that cluster its own campaign or product group with a higher budget ceiling. These products have already proven demand, so they deserve more aggressive bidding and should not be limited by a shared budget with slower-moving stock.

Clearance items deserve the opposite treatment. Tag them separately so you can either reduce bids to protect margin or, in some cases, raise bids briefly to move inventory faster, depending on your goal. Keeping clearance products in a distinct group also stops them from skewing performance data for the rest of your catalogue.

Use custom labels to structure Performance Max campaigns

Performance Max campaigns rely heavily on the signals in your product feed, since there are no keywords to target directly. Custom labels are one of the few levers you have to influence how Performance Max allocates spend across your catalogue.

Inside a Performance Max campaign, go to the listing group section and subdivide by custom label. This creates separate listing groups per label value, each of which can carry its own bid or exclusion. This is the practical mechanic behind every margin, seasonal, and top performer strategy described above.

A common mistake is treating Performance Max as fully automated and skipping this step. Smart Bidding will optimise within whatever structure you give it, but if every product sits in one undifferentiated group, it has no way to know that a high-margin top performers and a low-margin clearance item should be treated differently. <cite index="19-2">Custom labels do not change which queries your products match or who sees your ads, they exist purely so you can segment your catalogue and apply different bid targets per tier.</cite> That segmentation step is what makes Performance Max structurally aware of your business priorities rather than treating every SKU as equal.

For Shopify merchants who prefer an automated approach over manually maintaining five label definitions, a dedicated product segmentation tool can read live performance data and write custom labels back to Merchant Center on a schedule, which removes the need to update rules by hand as products move between margin or performance tiers.

Feed rules versus manual tagging

Feed rules and manual tagging solve different problems, and most Shopify stores end up using both.

They work well when the criteria are already in your feed and unlikely to need frequent manual review, such as price-based margin bands or product type clusters. Set the rule once in Merchant Center and it applies automatically as your feed updates.

Manual tagging through Shopify works better for judgment calls, such as marking a product as a Top Seller based on internal sales reporting that is not reflected in your feed data, or flagging a product for clearance ahead of a planned promotion.

Best practices for either approach are the same. Define each label clearly before you start. Apply it consistently across your full catalogue. Review your label values periodically, since a product that was high-margin last quarter may not be this quarter, and a stale label will quietly misallocate budget.

Best practices to avoid common mistakes

A few mistakes come up repeatedly with Shopify custom label strategies.

The first is using a custom label for something that changes too often to maintain manually, such as daily inventory levels. Custom labels are not built for real-time changes, so reserve them for values that are reasonably stable, like margin tier or category, and let feed rules or an automated tool handle anything that shifts frequently.

The second is overlapping definitions across the five available slots. If custom_label_0 and custom_label_1 both attempt to represent margin in slightly different ways, your product groups become harder to manage and your reporting gets confusing.

The third is setting up labels and never revisiting them. A seasonal label needs updating every season. A Best Seller label needs review as sales data changes. Treat your custom label strategy as something you maintain, not something you set once.

The fourth is exceeding what a single label can reasonably cover. If you find yourself trying to encode margin, season, and sales performance into one custom label value, split them across separate label slots instead. You have five to work with, so use more than one where it makes the structure clearer.

A fifth mistake worth flagging is skipping documentation. Write down what each custom label slot represents and the exact list of values it can take. This sounds unnecessary for a small catalogue, but as your team grows or you hand feed management to an agency, undocumented labels are one of the most common sources of reporting errors. A short reference sheet, even a simple one, saves hours of troubleshooting later when a product group stops matching what you expect.

It also helps to test one segmentation strategy at a time rather than launching margin, seasonal, and performance labels simultaneously. Add the margin label first, restructure your product groups, and give the campaign enough time to show a stable pattern before layering in a second label. This makes it far easier to attribute a change in performance to the specific segmentation you introduced, rather than guessing at which of three simultaneous changes caused the shift.

Frequently asked questions about custom labels

What is custom_label_0 used for? Custom_label_0 is simply the first of five available custom label fields in your Merchant Center feed. It has no fixed meaning. Many Shopify merchants use it for margin tier or season, since these are among the most commercially useful segmentation values, but the definition is entirely up to you.

How many custom labels can I use on Google Shopping? Google Merchant Center allows up to five custom labels per product, numbered custom_label_0 through custom_label_4. Each product can carry one value per label.

Do custom labels affect which Shopping ads show for a search? No. Custom labels do not influence which queries a product matches. That is controlled by your product titles, descriptions, and product type. Custom labels only affect how you can group and bid on products once they are already eligible to show.

Can I use custom labels in Performance Max campaigns? Yes. Custom labels work the same way in Performance Max as they do in standard Shopping campaigns. You subdivide listing groups by custom label value and apply different offers or exclusions to each group.

Should I tag products manually or use feed rules? Use feed rules for values that can be calculated from existing feed data, such as price-based margin bands. Use manual tagging for judgment-based labels, such as Best Seller status drawn from internal sales reporting. Many Shopify stores use a mix of both, and some move to an automated segmentation approach once their catalogue grows large enough that manual maintenance becomes a bottleneck.

Bringing the strategy together

Custom labels are not a single tactic. They are a framework you build once and refine over time. Start with the segmentation that matters most to your business, usually margin, then layer in seasonality and sales performance as your catalogue and campaign structure allow.

For a Shopify store, the goal is always the same: give Google Shopping and Performance Max enough signal to treat your products according to their actual business value, rather than bidding on every SKU as if it were interchangeable. A clear label strategy, applied consistently and reviewed on a regular schedule, is what makes that possible.

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