Best practices when using customer information for a Custom Audience

When making a Custom Audience based on information that customers have shared with you, include as much of it as possible to get the best match rates. This information – known as an "identifier" such as email address, phone number, address – may come from customer lists you've prepared, or from Meta pixel or offline events.

Once you've collected the information, format it into a CSV or TXT file. (View our guidelines for how to format Custom Audience lists).

If you're using multiple identifier types, make sure that your information is organised into separate columns that correspond to the types we accept. For example, don't include a single column for full names. Instead, include two columns – one for first names, one for surnames.

Separating each identifier into its own column header type ensures compatibility with the formats we accept before the information is hashed. (If you use your own column headers, you'll have to manually map an identifier to its type before uploading your list).

The two most important tips are:

• When using phone numbers on your list, always include the country code – even if all the numbers are from the same country.
• When using a country on your list, always include it in its own column – even if all your data is from the same country. (This is because we match on a global scale, so this helps us match as many people as possible from your list).

Note: Your file can be either CSV or TXT format. Download example files:

• Custom Audience example
• Offline conversions example

• How to edit a Custom Audience from a customer list
• Use a customer list to make a Custom Audience
• About hashing customer information