---
title: "What is Google Merchant Center? An advertiser's guide | Product Metrics"
description: "Google Merchant Center holds your product data and Google Ads runs the ads. See what changed in 2026 and how custom labels set priority per product."
canonical: "https://www.productmetrics.io/blog/what-is-google-merchant-center"
pageType: article
language: en
publisher: "Product Metrics"
author: "Berend Vrakking"
datePublished: 2026-10-07
dateModified: 2026-10-08
image: "https://www.productmetrics.io/og/blog/what-is-google-merchant-center.png"
---

> Content index: https://www.productmetrics.io/llms.txt

# What is Google Merchant Center? An advertiser's guide

## Key takeaways

- Merchant Center is a free Google tool for uploading product data, so products can appear across Google Search, Maps and YouTube. The ads run in Google Ads, paid per click.
- Custom labels (five attributes, one value each per product) are the main lever: Shopping and Performance Max groups can split on them. New labels can take 24-48 hours to appear.
- Use labels to read each product against its break-even ROAS (1 ÷ contribution margin). In the example, an account ROAS of 3.36 hides two products that lose €310 after ads.

Google Merchant Center is the free tool where you upload and manage your product data, so your products can appear across Google Search, Maps, YouTube and more ([Google Merchant Center Help](https://support.google.com/merchants/answer/188924)). It holds the products, and [Google Ads](https://support.google.com/google-ads/answer/2454022) runs the ads.

I wrote it for shop owners new to Merchant Center and for PPC specialists who run [Google Shopping ads](https://www.productmetrics.io/google-shopping-ads) or [Performance Max](https://www.productmetrics.io/performance-max). Feed basics live in [optimising Google Shopping ads](https://www.productmetrics.io/blog/optimize-google-shopping-ads); this guide covers what to set up so you can steer each product. The [Google Merchant Center](https://www.productmetrics.io/glossary/google-merchant-center) glossary entry has the short definition, and [Google Shopping management](https://www.productmetrics.io/blog/google-shopping-management) the weekly routine.

## Merchant Center, Google Ads and where products show

Merchant Center stores your product data, and Google Ads spends your budget. In Merchant Center you add products, fix issues and set labels. Google Ads is where campaigns, bids and budgets are set. Google's surfaces (Search, the Shopping tab, Images, YouTube and Maps) are where shoppers see the result.

Free listings can appear at no cost on Google Search, Maps, Gemini, YouTube, the Shopping tab, Images and Lens, and in most cases they are on by default. Google's [help centre](https://support.google.com/merchants) lists add-ons such as local inventory ads, promotions, vehicle ads and loyalty programs. Shopping ads are the paid layer. They "use your existing Merchant Center product data (not keywords)", and Google charges by cost per click, only when someone clicks ([Google Ads Help](https://support.google.com/google-ads/answer/2454022)).

![Flow from a primary data source into Merchant Center, then into linked Google Ads campaigns and on to Google surfaces, with an optional supplemental source feeding Merchant Center](https://www.productmetrics.io/images/blog/what-is-google-merchant-center/gmc-system-map.png)

_Products enter through a primary data source, labels can arrive through a supplemental source, and campaigns in the linked Google Ads account read the result._

## Six checks before labels

Labels only help when the basics are in place: a disapproved product or a mismatched item ID skews every product verdict that follows. Sign-up asks about your business, where you sell and how your products reach Merchant Center, and the Google Account you use needs admin access.

**Six checks before you use labels**

1. **Create the account.** Sign in with a Google Account email, which can create only one Merchant Center account. Enter your business details and where you sell. The country you choose cannot be changed later.
2. **Verify and claim your website.** One URL can be claimed by only one account, unless you use a multi-client account.
3. **Add your products as a primary data source.** Connect your platform (Google gives Shopify as an example), host a file Google fetches every 24 hours, or use Google Sheets or the Merchant API. Only a primary source can add or remove products.
4. **Link Google Ads.** You need the link before you can create Shopping campaigns.
5. **Clear the disapprovals.** Disapproved products don't appear on Shopping ads or free listings, so fix them before judging any product.
6. **Make item IDs and costs match.** Send the same item IDs in your conversion tag as the id in your feed, and add cost_of_goods_sold if you can. Google Ads uses both for product-level profit.

Products expire 30 days after their last refresh, unless you added them directly in Merchant Center. A re-submitted source, a scheduled upload or Google's own check of your website refreshes them. Google's steps are in [verify and claim](https://support.google.com/merchants/answer/11586344), [adding products](https://support.google.com/merchants/answer/11586438) (the [product feed](https://www.productmetrics.io/glossary/product-feed) entry defines the term) and [linking Google Ads](https://support.google.com/google-ads/answer/12499498). Disapprovals are in [Google's guide](https://support.google.com/merchants/answer/13693497).

The last check carries the profit logic. Google's cart data reports need the item IDs in your conversion tag to exactly match the `id` in your feed. Combined with `cost_of_goods_sold`, they let Google Ads generate metrics based on gross profit ([Google Ads Help](https://support.google.com/google-ads/answer/9028254)).

## What are custom labels in Merchant Center?

For an advertiser, [custom labels](https://www.productmetrics.io/glossary/custom-labels) are the main lever in Merchant Center. They are five attributes, `custom_label_0` to `custom_label_4`, that let you create filters for Performance Max, Shopping or Demand Gen campaigns, for reporting and bidding on groups of products. Shoppers never see them ([Google Merchant Center Help](https://support.google.com/merchants/answer/6324473)). The rules from that page:

- One value per attribute per product, 1-100 characters, not case sensitive.
- Up to 1,000 unique values per attribute, 5,000 in total. Labels beyond the limit are ignored for reporting and bidding.
- Not for Display with dynamic remarketing, which has its own attributes.

Give each slot one meaning. Google's best practice is one type of label per attribute, for example season in `custom_label_0`, selling rate in `custom_label_1` and price range in `custom_label_2`. Here is a slot plan to adapt. The meanings are a suggestion, because Google leaves them to you.

- `custom_label_0`: return against break-even, rewritten weekly. Values `above` and `below`.
- `custom_label_1`: margin band, changed monthly. Values `high-margin` and `low-margin`.
- `custom_label_2`: price band, changed with prices. Values such as `0-50` and `50-100`.
- `custom_label_3`: season or clearance, changed a few times a year. Values `winter` and `clearance`.
- `custom_label_4`: kept free for tests.

Mixing questions in one slot multiplies the values. Keep fast-changing labels apart from slow ones, so a weekly rewrite never touches your seasons.

**Figure: How many label values you maintain: one mixed slot against three clean slots.** Each bar is the number of custom label values to keep up to date. Season, margin band and price band in one slot need 48 combined values (4 × 3 × 4); giving each its own slot needs 11 (4 + 3 + 4).

| How the custom labels are set up | Label values to maintain |
| --- | --- |
| One mixed slot | 48 |
| Three clean slots | 11 |

_Source: Illustrative data. Calculated as 4 seasons × 3 margin bands × 4 price bands = 48, against 4 + 3 + 4 = 11_

## Three places to write a label

Pick the place by where the value comes from.

| Where | Use it for | Good to know |
|---|---|---|
| Primary feed | Values your shop or feed tool already holds, such as season | A file hosted at a URL is fetched every 24 hours |
| Attribute rules | Labels derived from data already in the feed, such as price bands | Needs the Advanced data source management add-on; rules run in order |
| Supplemental source | Values from outside the shop data, such as performance | Matches on `id`, cannot add products or stand alone, and needs the same add-on |

Google's example for rules is a price-range label set from the price you already submitted. Performance is not in the product data unless you add it, which is why performance labels usually travel in a supplemental source.

A [supplemental source](https://www.productmetrics.io/glossary/supplemental-feed) adds or overrides custom labels, promotion IDs and titles, can exclude products, and can add missing GTINs or local inventory data. It updates only products whose IDs are in a primary source ([Google Merchant Center Help](https://support.google.com/merchants/answer/15157604)). The tab appears only with the Advanced data source management add-on.

![A primary source with three products and empty labels, plus a supplemental source with labels matched on id, gives Merchant Center two labelled products and one empty, with an unmatched id ignored](https://www.productmetrics.io/images/blog/what-is-google-merchant-center/gmc-label-merge.png)

_The supplemental row finds its product by id and fills the label. An id that is not in the primary source changes nothing._

If your IDs differ between sources, custom data source matching joins them on another attribute such as brand, with a limit of 30,000 rows on the supplemental source ([Google Merchant Center Help](https://support.google.com/merchants/answer/15000309)).

## From label to campaign

A label does nothing until a campaign splits on it. In a Shopping campaign you subdivide product groups by custom label and set bids per group ([Google Ads Help](https://support.google.com/google-ads/answer/6275317)). In Performance Max you subdivide an asset group's listing group by custom label, and you can select Exclude on a group ([Google Ads Help](https://support.google.com/google-ads/answer/11596074)). [Performance Max for ecommerce](https://www.productmetrics.io/blog/performance-max-for-ecommerce) walks through the exclusion.

Labels also keep the structure small. An asset group can have up to 1,000 listing groups, and Google says a large number is not best practice and recommends grouping with custom labels.

**Figure: Listing groups needed to cover 5,000 products, against Google's limit of 1,000.** Each bar is the number of listing groups needed to cover 5,000 products. The dashed line is Google's limit of 1,000 per asset group. One group per product needs 5,000, five times the limit; one group per label value needs six.

| How the listing groups are split | Listing groups needed |
| --- | --- |
| One group per product | 5,000 |
| One group per label value | 6 |

Reference line: Google's limit per asset group (1,000).

_Source: Illustrative data: 5,000 products and six label values. Limit from Google Ads Help, Manage a Performance Max campaign with listing groups, checked 7 October 2026_

Allow 24-48 hours for new or edited labels to appear in Google Ads, and stay clear of the 1,000-value limit, because Google says a label may not sync when you are at or near it.

> **Sidenote:** A feed label (called a data source label on some Google pages) is a different thing. It chooses which data sources a campaign advertises, one per campaign, up to 20 characters. A custom label chooses products inside them ([Google Merchant Center Help](https://support.google.com/merchants/answer/14994087)).

## Worked example: a healthy account with two losing products

Six products over 30 days, revenue excl. VAT. Break-even ROAS is 1 ÷ contribution margin, which the [break-even ROAS calculator](https://www.productmetrics.io/break-even-roas-calculator) works out for any margin, and [break-even ROAS per product](https://www.productmetrics.io/blog/break-even-roas-per-product) shows step by step. POAS is ROAS × contribution margin, and break-even POAS is 1.0 ([POAS vs ROAS](https://www.productmetrics.io/blog/poas-vs-roas)).

| Product | Margin | Break-even ROAS | Spend | Revenue | ROAS | Contribution profit | After ads |
|---|---|---|---|---|---|---|---|
| Trail Runner 2 | 30% | 3.33 | €1,000 | €4,500 | 4.50 | €1,350 | +€350 |
| Winter Boot | 40% | 2.50 | €800 | €2,400 | 3.00 | €960 | +€160 |
| Everyday Sock | 20% | 5.00 | €300 | €1,200 | 4.00 | €240 | −€60 |
| Rain Jacket | 50% | 2.00 | €600 | €1,500 | 2.50 | €750 | +€150 |
| Gym Bag | 25% | 4.00 | €500 | €1,000 | 2.00 | €250 | −€250 |
| Water Bottle | 35% | 2.86 | €100 | €500 | 5.00 | €175 | +€75 |
| Account | 33.6% blended | 2.98 | €3,300 | €11,100 | 3.36 | €3,725 | +€425 |

*Illustrative data.*

The account returns 3.36 against a blended break-even of 2.98, which looks healthy until you read the rows.

**Figure: ROAS of six products against the ROAS each needs to break even.** Each product has two bars: the ROAS it gets and the ROAS it needs to break even. The dashed line is the account ROAS of 3.36. Four products get more than they need; Everyday Sock (4 against 5) and Gym Bag (2 against 4) get less and lose money.

| Product (contribution margin) | ROAS the product gets | ROAS needed to break even |
| --- | --- | --- |
| Trail Runner 2 (30%) | 4.5 | 3.33 |
| Winter Boot (40%) | 3 | 2.5 |
| Everyday Sock (20%) | 4 | 5 |
| Rain Jacket (50%) | 2.5 | 2 |
| Gym Bag (25%) | 2 | 4 |
| Water Bottle (35%) | 5 | 2.86 |

Reference line: ROAS of the whole account (3.36).

_Source: Illustrative data. Break-even calculated as 1 ÷ contribution margin; account ROAS calculated as total revenue ÷ total spend (€11,100 ÷ €3,300)_

Everyday Sock returns 4 and still loses money, because its 20% margin needs 5 (a POAS of 0.8). Rain Jacket returns only 2.50 yet clears its 2. A single account target would treat them the wrong way round.

**Figure: Contribution profit against ad spend in € for each product, last 30 days.** Each product has two bars: its contribution profit before ads and its ad spend. Where spend is the longer bar, the product loses money: Everyday Sock earns €240 on €300 of spend, and Gym Bag €250 on €500.

| Product | Contribution profit before ads | Ad spend |
| --- | --- | --- |
| Trail Runner 2 | €1,350 | €1,000 |
| Winter Boot | €960 | €800 |
| Everyday Sock | €240 | €300 |
| Rain Jacket | €750 | €600 |
| Gym Bag | €250 | €500 |
| Water Bottle | €175 | €100 |

_Source: Illustrative data. Contribution profit calculated as revenue (excl. VAT) × contribution margin_

Now write `above` or `below` to `custom_label_0` for each product, through a supplemental source, and wait 24-48 hours. In a Shopping campaign, the Products page in Google Ads has a Custom label column next to clicks and conversion metrics ([Google Ads Help](https://support.google.com/google-ads/answer/3455573)), and product groups or listing groups can split on the label.

**Figure: Contribution profit against ad spend in €, for products labelled above or below break-even.** Each group has two bars: its contribution profit before ads and its ad spend. The four products labelled above earn €3,235 on €2,500. The two labelled below take €800 of the €3,300 spend (24.2%) and earn €490, a €310 loss after ads.

| custom_label_0: ROAS above or below break-even | Contribution profit before ads | Ad spend |
| --- | --- | --- |
| above (4 products) | €3,235 | €2,500 |
| below (2 products) | €490 | €800 |

_Source: Illustrative data. Groups by whether ROAS is at or above the product's own break-even; spend share calculated as €800 ÷ €3,300_

Two of six products take 24.2% of the spend and lose €310 after ads. Compare each product's ROAS, or POAS, with its own break-even, label it `above` or `below`, and set priority per group. Check why the `below` group underperforms before you lower its priority. Do not judge a product on a handful of clicks, which [Google Shopping management](https://www.productmetrics.io/blog/google-shopping-management) covers.

## Google's price benchmark is a rough average

Google's Pricing tab, under Analytics in Merchant Center, compares your price with a benchmark: "the average price that typically leads to more successful ad auctions, impressions, clicks, or conversions", taken from retailers selling a product with the same GTIN. The price gap is the percentage difference between the two. You only get it for products with a valid GTIN ([Google Merchant Center Help](https://support.google.com/merchants/answer/9626903)).

Treat it as a rough signal, not a price to match. It is one aggregated number per product: you can't see which retailers it includes, how many there are, when their prices were read or what they charge for shipping. It also knows nothing about your margin, so read it next to profit, never instead of it.

| Product | Your price | Benchmark | Your price ÷ benchmark |
|---|---|---|---|
| Trail Runner 2 | €89.99 | €92.50 | 97.3% |
| Winter Boot | €129.99 | €124.99 | 104.0% |
| Everyday Sock | €9.99 | €9.50 | 105.2% |
| Rain Jacket | €79.99 | €79.99 | 100.0% |
| Gym Bag | €49.99 | €44.99 | 111.1% |
| Water Bottle | €14.99 | €16.00 | 93.7% |

*Illustrative data.*

Both products below break-even are priced above the benchmark. Real accounts will not line up so neatly, and the example is built to show the rule.

![Two by two grid of return against break-even and price against benchmark with an action in each cell: keep, keep, lower priority, and check the price first](https://www.productmetrics.io/images/blog/what-is-google-merchant-center/gmc-decision-grid.png)

_A product below break-even and above its benchmark price needs a price check before it loses priority._

### See exactly who you are compared with

[Competitor Prices](https://www.productmetrics.io/competitor-prices) shows what the benchmark hides. It scans competitor sites for the products that compete with yours, including own-brand products with no shared GTIN, matched by style, colour and the dimensions you define. For each product you see where your price ranks, the gap and why each match is comparable, with prices compared without shipping costs. You can monitor Google Shopping prices for the products you choose, daily, weekly or monthly. The price position sits next to POAS, margin and stock, and becomes a Merchant Center label your campaigns can use.

## Where Product Metrics fits

Product Metrics does the labelling from the worked example for you, with a finer split than `above` and `below`. [Product Segmentation](https://www.productmetrics.io/product-segmentation) uses ad clicks and ROAS to place each product in one of six segments, and writes the segment to a custom label, for example `custom_label_0` = `stars`, through a supplemental feed you add once. You approve every label it writes, and the label updates daily. You split campaigns or asset groups on it; bids and budgets stay with you.

It works on ROAS straight away and switches to POAS once you connect margins, which is when Everyday Sock's 0.8 shows up without a spreadsheet. Your feed itself stays in your shop or feed tool. Product Metrics has analysed more than 1M products, and my work was nominated at the Dutch Search Awards (Best Measurement Campaign 2023, Best Use of Data 2024).

## A first label in two days

For the weekly routine around labels, read [Google Shopping management](https://www.productmetrics.io/blog/google-shopping-management); for titles, images and feed quality, [how to optimise Google Shopping ads](https://www.productmetrics.io/blog/optimize-google-shopping-ads).

Clear your disapprovals first. Then decide what `custom_label_0` means, pick the ten products with the most clicks, and compare each with its own break-even ROAS. Write `above` or `below` in a supplemental source, and check your product groups or listing groups after two days.

## Sources

- [Get started with Merchant Center](https://support.google.com/merchants/answer/12159157) and [Free listings for products](https://support.google.com/merchants/answer/13889434)
- [Merchant Center Next is now Merchant Center](https://support.google.com/merchants/answer/17252069)
- [Create a product data source](https://support.google.com/merchants/answer/14990942) and [Set up your attribute rules](https://support.google.com/merchants/answer/14994083)
- [Custom label 0-4](https://support.google.com/merchants/answer/6324473) and [Use custom labels for Shopping ads](https://support.google.com/google-ads/answer/6275295)
- [Manage a Performance Max campaign with listing groups](https://support.google.com/google-ads/answer/11596074) and [About Pricing in Merchant Center Analytics](https://support.google.com/merchants/answer/9626903)
- [Delete the Merchant Center account](https://support.google.com/merchants/answer/9090515) and [Expiration date](https://support.google.com/merchants/answer/6324499)

## Frequently asked questions

### How much does Google Merchant Center cost?

Merchant Center itself is free, and Google says free listings can appear at no cost on Google Search, Maps, YouTube, the Shopping tab, Images and Lens. Advertising is paid: Shopping ads are charged by cost per click, and you pay only when someone clicks an ad.

### Is Merchant Center the same as Google Ads or Google Shopping?

You use it to upload and manage product data, fix issues and set custom labels. It is not Google Ads: campaigns run there, and they use the product data you keep in Merchant Center once the two accounts are linked. Google Shopping is where products show, because the Shopping tab is one of the places free listings can appear.

### Is Merchant Center Next a different tool?

It's now just called Merchant Center. Next replaced the classic experience for all retailers by September 2024, and in July 2026 Google removed the "Next" branding. Google says your account, product data, campaigns and features are unaffected, so guides about Next describe the same tool.

### How do I turn off or delete Google Merchant Center?

To stop free listings only, change their status on the Free listings page. To delete the account, an admin user has to do it: access ends immediately, your products are disapproved, and Shopping ads and free listings stop showing. You can create a new account at any time, and deleting it does not cancel Google Ads or delete your Google Account.

---

Written by Berend Vrakking, founder of Product Metrics. Last updated 2026-10-08.

HTML version: https://www.productmetrics.io/blog/what-is-google-merchant-center