# Using your Labelizer labels in Google Ads

> What Labelizer writes to your product feed, where to find it and how to use it.

After a run, [Labelizer](/docs/labelizer/labelizer) assigns every product to a performance bucket and
writes that bucket to your product feed as a custom label. You can then use that label to organize
and optimize your Google Ads campaigns.

## What Labelizer writes

Labelizer writes one thing: the product's bucket value into a single custom label slot in
Merchant Center. It does not change your titles, prices, descriptions or any other field in your
feed.

The value written is the bucket name itself, one of:

- `over-index` (your best performers, well above target)
- `index` (performing around target)
- `near-index` (close to target, room to grow)
- `under-index` (below target, spending more than it returns)
- `no-index` (little or no clicks and impressions, barely being shown)

If the project uses AOV segmentation, the value combines the AOV segment and the bucket, for
example `high-aov_over-index`. If the project uses Group by item_group_id, every variant in a group
receives the same value. See
[How Labelizer decides each bucket](/docs/labelizer/how-labelizer-decides-each-bucket).

So a product in the strongest bucket gets the custom label value `over-index`, and so on. See
[Understand Labelizer buckets and results](/docs/labelizer/understand-labelizer-buckets-and-results)
for what each bucket means, or
[How Labelizer decides each bucket](/docs/labelizer/how-labelizer-decides-each-bucket) for the exact
conditions behind them.

## Choosing your custom label slot

In your project settings, under Merchant Center, you choose which custom label slot (0 to 4)
Labelizer should write to. Pick a slot you are not already using for something else. The settings
screen shows how many values each slot has had in Google Ads over the last 30 days, so you can
avoid overwriting a label you already rely on.

Two requirements for syncing:

- Merchant Center must be connected to the project.
- The connected Google account needs admin access to the Merchant Center account. Read access
  alone is not enough to write custom labels.

Once sync is enabled, Labelizer updates the chosen slot automatically after every run.

## Checking the labels reached Merchant Center

In Merchant Center, open your products and add the custom label column for the slot you selected.
You should see the bucket values (`over-index`, `index` and so on) populated on your products.
Allow some time after a run for the sync to finish and for Merchant Center to refresh.

If the values don't show up, see
[Why Labelizer did not update custom labels](/docs/labelizer/why-labelizer-did-not-update-custom-labels).

## Checking the labels are in Google Ads

Custom labels flow from Merchant Center into Google Ads with the next feed update. This can take
up to 24 hours. Once available, the custom label appears as a product attribute you can filter and
segment on inside your Shopping and Performance Max campaigns.

## Next step

When the labels are visible in Google Ads, you are ready to build campaign segments around them.
See
[Segment your Google Ads campaigns with Labelizer buckets](/docs/labelizer/segment-your-google-ads-campaigns-with-labelizer-buckets).

The same buckets can also drive ChatGPT Ads campaigns, built from the Labelizer output rather than
from your feed by hand. See
[Build product campaigns from Labelizer](/docs/chatgpt-ads/build-product-campaigns-from-labelizer).