What is a labelizer? How to use one for Google Shopping

A labelizer is a tool that sorts every product in your Google Shopping feed into a performance group, such as best sellers, products that eat budget without selling, and products that get almost no traffic. It writes that group into one of the five custom label attributes in Google Merchant Center, usually every day. You then split your Shopping or Performance Max campaigns by that label, so each group gets its own budget and return target.

The name started as Producthero's product. Channable acquired Producthero, and as of October 21, 2026 Channable sells the Labelizer as part of its CSS offer. Today "labelizer" also describes any tool that does the same job. This guide explains how one works, what it writes into your feed, how to use the labels in campaigns, and how to tell whether you need one.

What does a labelizer do?

A labelizer connects two systems that do not talk to each other on their own. Google Ads knows how each product performs. Google Merchant Center (Merchant Center after this) holds your product data, the information Google uses to build your Shopping ads. A labelizer moves a summary of the first into the second. If you are new to Merchant Center, start with our guide to setting up a Google Merchant Center account.

It runs the same four steps on a schedule:

1. Read performance. It pulls clicks, cost, conversions and conversion value for each product from Google Ads, over a set period such as the last 30 days.
2. Classify. It compares each product to two thresholds you choose: a minimum number of clicks (enough traffic to judge) and a target ROAS. ROAS, or return on ad spend, is conversion value divided by cost. A product that spent $100 and brought $400 in sales has a ROAS of 400%.
3. Write the label. It sends the group name to Merchant Center as the value of a custom label, for example custom_label_3 = Heroes. Most tools do this through a supplemental data source, a secondary file that Google describes as a way to "provide more details or update existing details" for products already in your primary feed. Your main product feed is not touched.
4. Repeat. Labels refresh, usually daily, so a product that starts selling moves to a better group without anyone editing the feed.

The last step is what separates a labelizer from a label you type once. The value becomes a live signal your campaigns can react to.

What are custom labels in Google Merchant Center?

Custom labels are five optional product attributes, custom_label_0 to custom_label_4, that you define yourself. According to Google's custom label specification:

• Each product can hold one value per custom label, 1 to 100 characters long.
• Each attribute accepts up to 1,000 unique values across the account, and up to 5,000 values in total across all five.
• The values are never shown to shoppers.
• You can use them to filter products in Performance Max, Shopping and Demand Gen campaigns.

Google Ads Help adds that new or edited labels can take 24 to 48 hours to appear in Google Ads, and may not sync if you are at or near the Merchant Center attribute limit.

Google's own examples show the idea:

The first three rows come from Google's specification. The last row is what a labelizer adds: a value based on how the product performs rather than what it is.

How does a labelizer decide which label a product gets?

Most labelizers cross two questions: has the product had enough clicks to judge, and is its ROAS above your target? That gives four groups. Channable describes its Labelizer rules this way (as of November 2026):

Channable also offers an optional "0 Zombies" group for products with no impressions or clicks at all. Its advice is to set the click threshold slightly below the average number of clicks you need for one conversion, to set the labelizer's target ROAS about 25% below your actual ROAS, and to use a 30-day window in most cases. That labelizer target is only used to sort products. It does not change the bidding target in Google Ads.

A worked example

Say your click threshold is 50 and your labelizer target ROAS is 400%. Over the last 30 days:

• Product A: 120 clicks, $300 cost, $1,500 conversion value. ROAS 500%, high clicks: Heroes.
• Product B: 90 clicks, $250 cost, $400 conversion value. ROAS 160%, high clicks: Villains.
• Product C: 12 clicks, $30 cost, $150 conversion value. ROAS 500%, low clicks: Sidekicks.
• Product D: 8 clicks, $20 cost, no sales. ROAS 0%, low clicks: Zombies.

Products B and D cost about the same per click, but only B has had enough traffic to call it a problem. D simply has not been tested yet. That is why the click threshold matters as much as the ROAS target.

Other tools add inputs or groups. Clarmix's Product Labelizer uses clicks, target ROAS and cost per conversion to sort products into Profitable, High Potential, Low Potential, Costly, Zero Conversion and Zombies, updates them daily, and lets you build your own segments by combining rules. The demo video shows the setup.

Can you set custom labels without a labelizer?

Yes, and for many labels you should. There are three common ways, and all of them work well for data that already sits in your feed:

1. A column in your product file. Add custom_label_0 to your product data and fill in a value for each item. Fine for a few hundred products and stable values such as season.
2. A Google Sheet as a supplemental data source. Put the product ID and the label in a sheet that Merchant Center fetches on a schedule. Formulas can compute values such as price bands. Read more in our guide to supplemental feeds in Google Merchant Center.
3. Attribute rules (formerly feed rules). Inside Merchant Center you can set a custom label from conditions on other attributes, for example price or product_type. Google's help page says this needs the Advanced data source management add-on, which you turn on under Settings and Add-ons, and lets you test a draft rule before applying it.

The limit is the same for all three: they only see product data. Clicks, cost and ROAS live in Google Ads, not in your feed, so none of these methods can label a product by how it performs unless you export a report and paste it in by hand. A labelizer automates exactly that gap. Some advertisers fill it with a Google Ads script instead; our comparison of Flowboost labelizer script alternatives covers that route.

How do you use labelizer labels in Performance Max and Shopping campaigns?

A label does nothing until a campaign is split by it. The setup takes five steps:

1. Check which custom label slot is free. If custom_label_0 already holds season, point the labelizer at an empty slot so it does not overwrite your values.
2. Wait for the sync. Allow 24 to 48 hours for new values to reach Google Ads, then filter by the attribute in Merchant Center to confirm every product has a value.
3. Split the products. In Performance Max, open the campaign, go to Asset groups, then Listing groups, and subdivide by custom label. Google lists custom labels among the attributes you can use, next to category, brand, item ID and product type. In a Standard Shopping campaign, do the same with product groups.
4. Give each group its own target. The common setup is one campaign per main label, so Heroes and Villains get different target ROAS values and budgets. Products in the Zombies group often go in a separate campaign with a small budget so they can collect data.
5. Review after two to four weeks. Look at spend and conversion value by label, not only at the account average.

If you want to go further and sort by profit rather than revenue, our expert guide on how to segment Shopify products in Google Shopping by margin shows how to build margin labels next to performance labels.

Which labelizer tools exist in 2026?

Several feed and CSS vendors now ship a labelizer. Here is how they describe their tools on their own websites, as of November 2026:

The names differ but the model is close. When you compare, the questions that matter are whether you can change the thresholds, whether margin can be an input, how often labels refresh, and whether labels arrive through a supplemental source or require the tool to manage your main feed.

The right pick often depends on where your feed already lives. If you run your feed and CSS through Channable, its Labelizer is the simplest choice because it is already in the platform. The same goes for Bigshopper or adstrong CSS customers. A standalone labelizer makes more sense when you want to keep your current feed setup and only add performance labels on top. For a wider list, see our breakdown of Producthero alternatives for Google Shopping.

Do you need a labelizer?

Go through this checklist:

• Does your split depend on performance? If you want to group products by season, price or product type, attribute rules do it for free. If you want to group them by ROAS or wasted spend, you need performance data in the feed.
• Is the catalog too big to label by hand? With a few dozen products, a monthly export and a Google Sheet can work. With thousands, labels go stale before you finish.
• Is there enough data? Products need clicks before a label means anything. An account with few conversions will put most items in the low-click groups.
• Is conversion tracking right? Labels are only as good as the conversion values behind them. Wrong values sort products into the wrong groups.
• Will you change the campaign structure? Labels in the feed with no listing groups built on them change nothing.

If the first answer is yes and the last three are covered, a labelizer will save you a weekly manual job.

What mistakes should you avoid with a labelizer?

• Cutting Zombies off completely. Low-click products include new arrivals that have not been tested. Give them a small budget instead of excluding them all.
• Confusing the labelizer target with your bid target. The threshold used to sort products is not the target ROAS in your campaign settings.
• Too many groups. Each extra group splits your conversion data further. Four to six groups is the usual range across the tools above.
• Changing thresholds every week. Products then jump between campaigns and each group never builds a stable history. Channable, for example, calls its Labelizer an always-on setup that you usually do not need to change each month.
• Overwriting another label. Keep a written note of what each of the five slots holds.

Frequently asked questions

Is labelizer a brand name or a generic term?

Both. Labelizer was Producthero's product name and is now sold by Channable after it acquired Producthero. The word is also used for any tool that writes performance-based custom labels to Merchant Center, such as adstrong Studio Labelizer and Feedoptimise Feed Labelizer.

Is Producthero still available?

Producthero is now part of Channable. Channable's help center says Producthero CSS accounts began migrating to Channable in batches starting April 2026, and the Labelizer is included in Channable's CSS Pro plan.

How many custom labels can I use?

Five per product, custom_label_0 to custom_label_4, with one value each. Google allows up to 1,000 unique values per attribute and 5,000 in total across the account.

Can attribute rules set custom labels based on ROAS?

Not on their own. Attribute rules work with data in your product feed, and ROAS comes from Google Ads. You need a labelizer, a script or a manual export to bring performance into the feed.

Do custom labels work in Performance Max?

Yes. Google supports custom labels in Performance Max, Shopping and Demand Gen campaigns, and lists them as an attribute for listing groups in Performance Max asset groups.

Sources

• Google Merchant Center Help: Custom label [custom_label_0-4]
• Google Ads Help: Use custom labels for Shopping ads
• Google Ads Help: Manage a Performance Max campaign with listing groups
• Google Merchant Center Help: Create a product data source
• Google Merchant Center Help: Set up your attribute rules
• Channable: Channable Labelizer, product segmentation for Google Ads (October 21, 2026)
• Channable: Labelizer for Google Ads
• Channable Help Center: Migrate from Producthero to Channable
• adstrong: Studio Labelizer
• Bigshopper: LabelWiser
• Label Up: Smart labels
• Feedoptimise: Feed Labelizer
• Clarmix: Product Labelizer

Cover photo by Angèle Kamp on Unsplash.