Beginning September 2, 2025, we will start to roll out more proactive restrictions on custom audiences that may suggest information not permitted under our terms. For example, any custom audience or lookalike audience suggesting specific health conditions (e.g., “arthritis”, “diabetes”) or financial status (e.g., “credit score”, “high income”) will be flagged and prevented from being used to run ad campaigns.

What these restrictions mean for your campaigns:

You won’t be able to use flagged custom audiences when creating new campaigns.

If you have an active campaign using flagged custom audiences, you should edit or pause it and choose a different audience to avoid performance and delivery issues.

For API developers:

Beginning September 2, 2025, operation_status will return 471 to signal if your custom audiences have been flagged.

More information on this update and how to resolve flagged custom audiences can be found here⁠.

Target people most like your established customers. Lookalike audiences take several sets of people as “seeds” then Facebook builds an audience of similar people. You can use lookalikes for any business objective: Targeting people similar your customers for fan acquisition, site registration, off-Facebook purchases, coupon claims, or simply to drive awareness of a brand.

Seed audiences can be:

Existing Custom Audiences

Campaign or Ad Set conversions

Page fans

Facebook refreshes members in a lookalike every 3 days if the lookalike belongs to an adgroup.

Create

Lookalike audiences can take 1-6 hours to fully populate. While audiences populate, you can create and run ad sets targeting the audience. Once the audience is ready, Facebook delivers to people populated in the audience and ads delivery will catchup and work as normal. See Delivery Status. Create a new lookalike audience at: https://graph.facebook.com/{API_VERSION}/act_{AD_ACCOUNT_ID}/customaudiences.

Example creation call for lookalike from a custom audience:

curl \
  -F 'name=My lookalike audience' \
  -F 'subtype=LOOKALIKE' \
  -F 'origin_audience_id=<SEED_AUDIENCE_ID>' \
  -F 'lookalike_spec={"type":"similarity","country":"US"}' \
  -F 'access_token=<ACCESS_TOKEN>' \
https://graph.facebook.com/v25.0/act_<AD_ACCOUNT_ID>/customaudiences

To create lookalike audiences with PHP Ads SDK⁠ or Python Ads SDK⁠, use CustomAudience.

The response contains:

Name	Description
`id` type: integer	ID of lookalike audience

Custom Audience Lookalike

If you have a Custom Audience with at least 100 people, you can build lookalike audiences based on it. This includes Custom Audiences for your Website and Custom Audiences for your Mobile App.

Name	Description
`name` type: string	Required. Custom Audience name
`origin_audience_id` type: long	Required. ID of Custom Audience. Origin audiences must have at least 100 members.
`lookalike_spec` type: array	Required. See description below.
`lookalike_spec.type` type: string	Required. Set either `type` or `ratio`. `similarity` or `reach`
`lookalike_spec.starting_ratio` type: float	Optional. Start percentage for lookalike. For example, `starting_ratio` 0.01 and `ratio` 0.02 creates a lookalike from 1% to 2% of a lookalike segment. `starting_ratio` must be less than ratio
`lookalike_spec.ratio` type: float	Required. Set either `type` or `ratio`. `0.01`-`0.20` incremented by 0.01. Top x% of original audience in a selected country
`lookalike_spec.allow_international_seeds` type: boolean	Optional. At least 100 seed audience members from a country. If not, `allow_international_seeds` set to `true` means Facebook finds this minimum number of audience members in another country. Default `false`.
`lookalike_spec.country` type: string	Required. Set `country` or `location_spec`. Find lookalike audience members in this country
`lookalike_spec.location_spec` type: array	Required. Either `country` or `location_spec`. Find audience members in these locations. List of countries or country groups such as `Asia`
`lookalike_spec.location_spec.geo_locations` type: array	Required. At least one entry under `countries` or `country_groups`. Include these locations
`lookalike_spec.location_spec.geo_locations.countries` type: array of strings	Optional. Target countries. Array of country codes, see Targeting Search API, Countries. Example: `'countries': ['US']`
`lookalike_spec.location_spec.geo_locations.country_groups` type: array of strings	Optional. Target countries in global regions and free trade areas. Array of country group codes. For full options, see Targeting, Location, `country_groups` and Targeting Search, `country_groups`. Example: `'country_groups': ['asia','mercosur']`
`lookalike_spec.location_spec.excluded_geo_locations` type: array	Optional. Locations to exclude
`lookalike_spec.location_spec.excluded_geo_locations.countries` type: array of strings	Optional. Same as `countries` under `geo_locations`
`lookalike_spec.location_spec.excluded_geo_locations.country_groups` type: array of strings	Optional. Same as `country_groups` under `geo_locations`

Types

Optimize your audience for “Similarity” or “Greater reach”.

Similarity - Audience includes the top 1% of people in a selected country who are most similar to the seed Custom Audience. The new audience’s reach is smaller, matching is more precise.

Greater Reach - Audience includes the top 5% of people in the selected country that are similar to the seed Custom Audience, but with a less precise match.

Instead of using types you can manually set ratio to represent the top x% of the audience in the selected country. ratio should be from 1%-20% and in intervals of 1%.

Campaign or Ad Set Conversion Lookalikes

Facebook has campaign and ad set conversion lookalikes to target people similar to those converting from previous or current campaigns or ad sets; for example, campaigns or ads that are optimizing for conversions. We measure conversions based on a campaign or ad set type in Conversion Specs. For example, target people that took action on your website or installed your app within 28 days of clicking your ad.

curl \
  -F 'subtype=LOOKALIKE' \
  -F 'lookalike_spec={
    "origin_ids": "<CAMPAIGN_ID>",
    "starting_ratio": 0.03,
    "ratio": 0.05,
    "conversion_type": "campaign_conversions",
    "country": "US"
  }' \
  -F 'access_token=<ACCESS_TOKEN>' \
https://graph.facebook.com/v25.0/act_<AD_ACCOUNT_ID>/customaudiences

You need at least 100 unique conversions from your campaigns or ad sets. More converters result in a better predictive model and we suggest 200 or more members who converted. You should also select campaigns or ad sets with similar objectives.

To create this lookalike, specify one or more of your campaigns or ad sets. For example, specify one campaign and two ad sets of another campaign.

Facebook uses up to 180 days of past conversion data and identifies people converting on your campaigns and ad sets as examples. We train prediction model then create a lookalike audience. Facebook constantly updates the underlying prediction model as campaigns or ad sets get new conversions.

Name	Description
`lookalike_spec` type: array	Required. See description below.
`lookalike_spec.origin_ids` type: array of integers	Required. Array of ad object ids. People who convert on these ads are used to model a lookalike. One or more campaign IDs or ad set IDs, or a mix of them.
`lookalike_spec.conversion_type` type: string	Required. `campaign_conversions`. Indicates audience is a campaign conversion lookalike
`lookalike_spec.country` type: string	Required. Country to find lookalike members.
`lookalike_spec.allow_international_seeds` type: boolean	Optional. At least 100 seed audience members from a country. If not, `allow_international_seeds` set to `true` means Facebook finds this minimum number of members in another country. Defaults to `false`.
`lookalike_spec.starting_ratio` type: float	Optional. Start percentage for lookalike. For example, `starting_ratio` 0.01 and `ratio` 0.02 creates a lookalike from 1% to 2% of a lookalike segment. `starting_ratio` must be less than `ratio`
`lookalike_spec.ratio` type: float	Required. Range of `0.01`-`0.20`. Top x% of original audience in the selected country.

Currently, the following campaign conversion types are eligible for Lookalike Audiences:

Link clicks

Offer ads

Page likes

Canvas App installs

Event responses

Post engagement

Website conversions

Mobile app installs

Mobile app engagement

Video views

Local awareness

Page Fan Lookalikes

Create a lookalike audience based on people who like your Page:

curl \
  -F 'subtype=LOOKALIKE' \
  -F 'lookalike_spec={
    "ratio": 0.01,
    "country": "US",
    "page_id": "<PAGE_ID>",
    "conversion_type": "page_like"
  }' \
  -F 'access_token=<ACCESS_TOKEN>' \
https://graph.facebook.com/v25.0/act_<AD_ACCOUNT_ID>/customaudiences

Name	Description
`lookalike_spec` type: array	Required. See description below.
`lookalike_spec.page_id` type: int	Required. Facebook ID of the page whose fans will be used for the lookalike
`lookalike_spec.conversion_type` type: string	Required. `page_like` - Indicates that this is a page fan lookalike
`lookalike_spec.country` type: string	Required. The country to find the lookalike people. The default is ‘US’
`lookalike_spec.allow_international_seeds` type: boolean	Optional. You need at least 100 seed audience members from a country. If this minimum is not satisfied, `allow_international_seeds` set to `true` means Facebook finds this minimum number of seed audience members in another country. Defaults to `false`.
`lookalike_spec.starting_ratio` type: float	Optional. Starting percentage of the lookalike. For example, a starting_ratio of 0.01 and a ratio of 0.02 would create a lookalike from the 1% to 2% lookalike segment. The value of starting_ratio should always be less than that of ratio
`lookalike_spec.ratio` type: float	Required. Range 0.01-0.20. How much of the country the lookalike should target.

Flagged custom and lookalike audiences

If the seed audience is flagged with an operation_status of 471, attempts to create a lookalike audience based on the seed audience will fail with an error.

{
  "error": {
    "message": "Invalid parameter",
    "code": 100,
    "error_subcode": 1713232,
    "error_user_title": "Seed audience restricted",
    "error_user_msg": "The seed audience you selected cannot be used to create a lookalike audience because it has integrity restrictions. Please use a different seed audience",
  },
}

Targeting

Targeting lookalikes is the same as targeting Custom Audiences. See Custom Audiences, Targeting. This also applies for exclusion targeting and conjunctive AND targeting. To target when you create an ad:

curl \
  -F 'name=My AdSet' \
  -F 'optimization_goal=REACH' \
  -F 'billing_event=IMPRESSIONS' \
  -F 'bid_amount=2' \
  -F 'daily_budget=1000' \
  -F 'campaign_id=<CAMPAIGN_ID>' \
  -F 'targeting={
    "custom_audiences": [{"id":"<LOOKALIKE_AUDIENCE_ID>"}],
    "geo_locations": {"countries":["US"]}
  }' \
  -F 'status=ACTIVE' \
  -F 'access_token=<ACCESS_TOKEN>' \
https://graph.facebook.com/v25.0/act_<AD_ACCOUNT_ID>/adsets

More examples at Targeting Specs.

Managing Audiences

Get details on custom audiences used to create lookalikes as well as lookalikes. We return the same fields as Custom Audiences. Below is a sample response for a Custom Audience used to create lookalikes. lookalike_audience_ids specifies which lookalike audiences were generated from this audience.

 {
  "id": "6006164557194",
  "account_id": 12345,
  "approximate_count": 816400,
  "lookalike_audience_ids": [
    6006183285954,
    6006183285955
  ],
  "name": "Boys Apparel",
  "parent_audience_id": 0,
  "parent_category": "Custom",
  "status": "ready",
  "subtype": "CUSTOM",
  "type": 4,
  "type_name": "Advertiser Generated",
  "time_updated": 1362439491
},

Lookalike audiences contain a subtype of 2. We also return lookalike_spec, an array in this format:

Name	Description
`type` type: string	`similarity`, `reach` or `custom_ratio` - Always returned
`starting_ratio` type: float	Returned if `starting_ratio` specified
`ratio` type: float	Multiple of `0.01`. Returned if `type` is `custom_ratio`
`country` type: string	Country code
`origin` type: array	See description below.
`origin.deleted` type: boolean	`true`, Returned when the origin deleted
`origin.id` type: int	Origin ID
`origin.name` type: string	Origin name
`origin.type` type: string	`custom_audience` or `page`
`target_countries` type: array of strings	All countries used to create audience

Another audience below where subtype is LOOKALIKE:

{
 "id": "6006183285954",
 "account_id": 12345,
 "approximate_count": 1782100,
 "name": "Boys Apparel_lookalike_US_Similarity",
 "origin_audience_id": 6006567610735,
 "parent_audience_id": 0,
 "parent_category": "Custom",
 "status": "ready",
 "subtype": "LOOKALIKE",
 "type": 4,
 "type_name": "Advertiser Generated",
 "time_updated": 1362506552
},

Delivery Status

After you create a lookalike audience we return a Custom Audience ID. It can take about one hour to fully populate an audience. You can get the status at: /{lookalike_audience_ID}?fields=delivery_status. This returns a JSON response with delivery_status or code 200 if an audience populates:

"delivery_status": {
  "code": 200,
  "description": "This audience is ready for use."
},

For testing, you should check the status of the list with Ads Manager⁠.

To delete a lookalike audience, you do the same as you do for Custom Audiences.

Inactive Audiences

A Lookalike audience is considered inactive when it has not been used in active ads for 90 days. Inactive lookalike audiences have different approximate_count, operation_status, and delivery_estimate.

Field	Changes for Inactive Lookalikes
`approximate_count`	You are not able to retrieve a size. A call for this field returns `-1` for inactive lookalikes.
`operation_status`	`450`: This lookalike audience is inactive. It can be used in ads but will not have an estimate till the campaign is published. `100`: If an audience hasn’t been used in an active ad set for over 2 years, it will begin to expire. Expiring audiences that remain unused for 90 days will be deleted. `471`: The lookalike audience has been flagged for integrity reasons.
`delivery_estimate`	You are not able to retrieve a delivery estimate. A call for this field returns `-1` for inactive lookalikes. This field is available under Ad Account and Ad Set nodes. Both exhibit the same behavior for inactive lookalikes.
`delete_time`	When an audience’s `operation_status` has been marked as expiring (code `100`), the `delete_time` field tells you in Unix time when the audience will be deleted.

You can still start a campaign using an inactive lookalike audience. The reach estimate information is available after your new ad gets published.

Deletion

For all advertisers beginning June 8, 2021 and going forward, we will automatically be moving audiences to the “Expiring Audience” stage once they have been inactive for over two years. This means that once an audience meets the threshold of not being used in an active ad set for over two years, it will be automatically flagged as an “Expiring Audience”, and the delete_time field will be marked with the estimated deletion time (i.e., 90 days from the time of flagging) when the audience is scheduled to be deleted.

You will then be able to either proactively delete the audience or use the audience in an active ad set to prevent deletion. You can see which of your audiences are in the expiring stage at any time by filtering on their operation_status or delete_time fields.

For more information, see the Custom Audiences Overview documentation.

Best Practices

Seed Custom Audience - Make it as large as possible so we have enough data to find similar people.

Combine Lookalikes - With other Facebook’s targeting for additional demographics or interests.

If your seed audience has attributes such as gender or geography, the lookalikes generate may not adhere to those attributes.

Upcoming Lookalike Changes

UPDATED APRIL 28, 2021: The removal of thelocation_spec and country parameters from lookalike audience creation is currently delayed. Updates on when this change will go into effect will be forthcoming.

We will remove the location_spec and country parameters from lookalike audience creation. The location for the lookalikes will be defined by the country location in the campaign’s targeting specification. The target location won’t be a part of the lookalike audience specification. The reach estimate of the campaign using a newly created lookalike will be populated only in a few hours after the ad being published.

There will be no impact on existing campaigns given this change. This requirement will only impact new and edited campaigns.

We will automatically convert legacy lookalike audiences into new lookalikes without target locations.

Changes to Lookalike Creation

Location parameter changes

Endpoint: act_{AD_ACCOUNT_ID}/customaudiences

Example Request

curl POST \
  -F 'name=My lookalike audience' \
  -F 'subtype=LOOKALIKE' \
  -F 'origin_audience_id=<SEED_AUDIENCE_ID>' \
  -F ‘lookalike_spec={
  "is_financial_service":false,
  "allow_international_seeds":true,
  "ratio":0.01,
  "type":"custom_ratio"}
    ’}\
  -F 'access_token=<ACCESS_TOKEN>' \
  https://graph.facebook.com/v2.11/act_<AD_ACCOUNT_ID>/customaudiences

The following parameters will be ignored if passed during creation:

lookalike_spec.country

lookalike_spec.location_spec

lookalike_spec.location_spec.geo_locations

lookalike_spec.location_spec.geo_locations.countries

lookalike_spec.location_spec.geo_locations.country_groups

lookalike_spec.location_spec.excluded_geo_locations

lookalike_spec.location_spec.excluded_geo_locations.countries

lookalike_spec.location_spec.excluded_geo_locations.country_groups

Size parameter changes

Endpoint: act_{AD_ACCOUNT_ID}?fields=approximate_count

There will be no size associated with new lookalike audiences, and the approximate_count field will return -1 for all lookalike audiences.

Example Response

{
    "approximate_count": -1,
    "id": "6126486105659",
}

Delivery and operation status

Endpoints:

{AD_ACCOUNT_ID}?fields=delivery_status

{AD_ACCOUNT_ID}?fields=operation_status

The delivery_status field for old lookalike audiences with location specifications will return a code 400 with a This audience is disabled. description. For new lookalike audiences it will return a code 200 response.

The operation_status field will return a retirement notification for old lookalike audiences with location specifications. For new lookalike audiences it will return a code 200 and Normal description response.

See Custom Audiences for more information about these fields.

Changes to Ad Sets

Ad creation and editing

We will automatically upgrade ads to use new lookalikes if the targeting of the existing campaigns containing the legacy lookalike is edited. The legacy lookalike will no longer be available for use in newly created ad campaigns.

With location specifications removed from lookalike audience creation, you will need to set location targets during Ad Set creation. Attempting to create an Ad Set without location targeting will result in an error.

All the above changes will also be applicable when audiences are included in excluded_custom_audiences, flexible_spec, and exclusions in the campaign.

Endpoint: act_{AD_ACCOUNT_ID}/adsets

Example Request

curl POST \
  -F 'targeting={
        "geo_locations":{
            "countries":["US"],
        },
        "age_min":25,
        "age_max":40,
        "custom_audiences":[{"id": <CUSTOM_AUDIENCE_ID>}]
  ‘}\
  -F 'access_token=<ACCESS_TOKEN>' \
  https://graph.facebook.com/v2.11/act_<AD_ACCOUNT_ID>/adsets

Attempting to create an Ad Set without location targeting will result in an error.

{
  "error": {
    "message": "Invalid parameter",
    "type": "FacebookApiException",
    "code": 100,
    "error_data": {
      "blame_field_specs": [["targeting" ] ]
    },
    "error_subcode": 192342134,
    "is_transient": false,
    "error_user_title": "Missing Location while using Lookalike",
    "error_user_msg": "You need to use a location with your lookalike    audience.",
    "fbtrace_id": "F78cCCJoZPx"
  },
  "__fb_trace_id__": "F78cCCJoZPx",
  "__www_request_id__": "AcwlIc7_uK5uTXjzjIa38yc"
}

If you try to edit an Ad Set containing a shared legacy lookalike and don’t have a corresponding new lookalike in the owning ad account, an error will occur. Request the owning ad account share the new lookalike audience with you to resolve the issue.

{
  "error": {
    "message": "Invalid parameter",
    "type": "FacebookApiException",
    "code": 100,
    "error_data": {
      "blame_field_specs": [["targeting" ] ]
    },
    "error_subcode": 192342135,
    "is_transient": false,
    "error_user_title": "",
    "error_user_msg": "Please ask the owner of the audience 1234 to share the new lookalike which does not contain location with you. You will be able to use the new audience"
    "fbtrace_id": "F78cCCJoZPx"
  },
  "__fb_trace_id__": "F78cCCJoZPx",
  "__www_request_id__": "AcwlIc7_uK5uTXjzjIa38yc"
}

During the rollout period of these changes, sharing lookalikes between ad accounts in the rollout and ad accounts not in the rollout is not supported via the API. Please use Audience Manager to handle the sharing. After May 24, 2021, you can continue to use sharing via API in the following developer document to share new lookalike audiences between ad accounts.

Endpoint: {AD_ACCOUNT_ID}/adaccounts?adaccounts={SHARED_TO_AD_ACCOUNT_ID}

Reach and delivery estimate changes

Endpoints:

act_{AD_ACCOUNT_ID}/reachestimate

act_{AD_ACCOUNT_ID}/delivery_estimate

These endpoints will return a new targeting_status parameter with one of the following descriptions:

lookalike_container_without_country — A new lookalike does not have a country specified in the campaign targeting. A country is needed to see the estimated users number.

lookalike_container_without_delivery_lookalike — A new lookalike does not have a corresponding backend lookalike. The new lookalike needs to be used in an Ad Set for it to actually have reach.

none — There is no issue with the reach.

The reachestimate endpoint will return -1 for the users parameter the first time a new lookalike audience and country target is used; thereafter the estimated user count will be returned.

The estimate_dau and estimate_mau parameters will return -1 for the users parameter the first time a new lookalike audience and country target is used; thereafter the estimated user count will be returned..

Example Responses

// Reach estimate response
{
    "users": -1,
    "estimate_ready": true,
    "targeting_status": "lookalike_container_without_delivery_lookalike"
}

// Delivery estimate response

{
    "data": [{
        "daily_outcomes_curve": [{
            "spend": 0,
            "reach": 0,
            "impressions": 0,
            "actions": 0
        }],
        "estimate_dau": -1,
        "estimate_mau": -1,
        "estimate_ready": true ,
        "targeting_status": "lookalike_container_without_delivery_lookalike"
    }]
}

FAQ

When will these changes go into affect?

Will I be able to share the new Lookalikes that don’t have location specs with other ad accounts still under legacy Lookalikes during the release?

During the period between Marketing API v10 and v11, sharing lookalikes between ad accounts in the rollout and ad accounts not in the rollout is not supported via the API. Please use Audience Manager to handle the sharing. After the release of Marketing API v11, you can continue to use sharing via the API to share new lookalike audiences between ad accounts.

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Lookalike Audiences