What are custom audiences?
Nicklas Segatz Mortensen · Growth Hacker · Fractional CMO · Meta Ads Nerd · 8 July 2026 · 3 min.
Definition
A custom audience is an audience you build from your own data: customer lists, website visitors (via pixel/CAPI), app activity, video viewers or engagement on Meta.
Also called: Custom Audience, Custom audiences
Sådan virker det
En custom audience bygges på dine egne data — kundelister, website-besøgende, video-seere, engagement. Den bruges både til retargeting (nå dem igen) og som seed til lookalikes (find flere som dem). Ren, samtykket førstepartsdata er guld her.
01Two roles: reach again and find more
Custom audiences serve two main purposes. For retargeting: reach people who've already interacted — visited the site, added to cart, watched a video. And as a seed for lookalikes: use a high-value customer list to find new, similar people. Same data foundation, two uses.
The value rises and falls with data quality. An up-to-date, consented customer list with email and phone matches far better than a thin visitor list — and a solid server-side setup makes sure website-based custom audiences don't leak as cookie restrictions tighten.
Frequently asked questions
What can I build a custom audience on?+
Customer lists (email/phone), website visitors via pixel and CAPI, app activity, video viewers, and engagement on your Meta profiles. The cleaner and more current the data, the better the audience matches.
Is a custom audience the same as a lookalike?+
No. A custom audience is your own, known contacts/visitors. A lookalike is new, unknown people who resemble a seed. Often a custom audience is used precisely as the seed to build a lookalike.
Related terms
Glossary
What are lookalike audiences?
A lookalike audience is an audience Meta builds by finding new users who statistically resemble a seed audience you provide — for example your buyers or your most valuable customers.
Read the entry →Glossary
What is retargeting?
Retargeting (remarketing) is advertising aimed at people who've already interacted with you — visited the site, viewed a product, or added to cart without buying.
Read the entry →Glossary
What is server-side tracking?
Server-side tracking sends conversion events from your own server (e.g. via a server-side Google Tag Manager container and Meta's Conversions API) instead of from the user's browser — so data isn't lost to ad blockers, cookie restrictions and iOS limitations.
Read the entry →
Nicklas Segatz Mortensen
Growth Hacker · Fractional CMO · Meta Ads Nerd at Oaksmond
Growth hacker and fractional CMO with 10+ years' experience and hundreds of millions in managed ad spend behind him. Background from larger Danish and international scale-ups, and from the agency world.
Meet the team →