1. Log in to your Ads Manager.

2. Click the menu in the top corner and select 'Audiences.'

3. Click ‘New Audience' and select 'Custom Audience'

4. Select 'Customer List.'

5. Drag and drop or click to upload your customer list file or copy and paste values into the upload dialogue. You can download the example files for reference by clicking on the links above the upload dialogue. Files should follow these formatting rules:

• A single column of emails or mobile advertising IDs or phone numbers.
• Do not Mix emails, mobile advertising IDs, or phone numbers in the same file.
• File extension should be .csv or .txt
• Always include the country code in your customers’ phone numbers, such as 1 for United States, 44 for United Kingdom, and 33 for France. As a best practice, remove any non-numeric characters.
• There is no hard limit on file size, but try keeping the file size below 1GB. You can also upload additional files to an audience after your initial upload.

6. Enter your snap audience name and description.

7. Click ‘Upload.’

To get your Snapchat Segment ID, follow the steps below:

1. Log into your Snapchat Ads Manager dashboard.
2. Go to Assets > Audiences.
3. Under Audience Library, select the required audience in the dropdown.
4. Copy the ID after /audiences/custom-audience/ in the URL of the resulting page. This is your segment ID.

Custom audiences help you reach your ideal snapchat audience by setting up unique targeting options such as entering relevant keywords and URLs. For example, you can configure a custom audience segment in your display, gmail, and video campaigns by simply adding specific keywords, URLs, and apps related to your product or service.