About customer list custom audiences on Meta, explained
Meta’s help article “About customer list custom audiences” only loads with JavaScript. Here it is in plain words, with the steps and examples, from Meta’s help center as read on October 9, 2026.
On this page · 8 sections
- What is a customer list custom audience?
- Which identifiers can a customer list contain?
- How do hashing and matching protect your customer data?
- How do you create a customer list custom audience?
- What does the match score tell you?
- When should you choose Only exclusions?
- What are the access rules and limits?
- How does Adwize work with your customer lists?
A customer list custom audience is an audience you build from information you already hold about your customers, such as emails, phone numbers and addresses. Meta calls these details identifiers. You upload them as a CSV or TXT file, or paste them, and they are hashed on your own machine before they reach Meta. Meta then matches the hashed values with profiles so you can show ads to those people on Facebook, Instagram and Meta Audience Network. The more identifiers you give, the better the match rate, and Meta says it learns no new identifying information from hashed data. You create the audience in Ads Manager, under Audiences, with Customer list. You need the right access to an ad account linked to a business portfolio, a legal basis for the data, and no prohibited information such as health or financial details. A match score out of ten then tells you how well the list matched.
TL;DR
- A customer list custom audience matches your own customer data, such as emails and phone numbers, with Meta profiles.
- The list is a CSV or TXT file. It is hashed on your machine before it is sent to Meta.
- More identifiers per person give a better match rate. The Match score column rates it out of ten.
- You need ad account access through a business portfolio, a legal basis, and no sensitive data in the list.
- Adwize shows which audience a campaign uses in plain words and waits for your approval before launch.
What is a customer list custom audience?
It is an audience made from information you have collected about your own customers and shared with Meta. The goal is to reach people who have already shown an interest in your business or product, such as past buyers, subscribers or leads, with ads on Facebook, Instagram and Meta Audience Network.
Meta’s create page describes it as an ad targeting option that helps you find your existing audiences among people across Meta technologies. In other words, it starts from a list you own, not from behavior Meta observed on your website or app.
That is the difference with the other custom audiences. A website audience comes from your pixel, and an engagement audience from people who interacted with your Page or videos. For using those to bring visitors back, see our guide to Facebook retargeting ads.
Which identifiers can a customer list contain?
Meta calls each piece of customer information an identifier. The most common are email addresses, phone numbers, names and postal addresses. A customer list is simply a CSV or TXT file holding these identifiers, one customer per row, which Meta uses to build the audience by matching it with profiles.
The rule that matters most: the more identifiers you provide for each person, the better your chances of a good match rate. An email alone can miss someone who signed up to Facebook with another address. An email plus a phone number plus a name gives Meta more ways to find them.
Meta adds a note on mobile advertiser IDs. Since Apple’s iOS 14 changes, matching on that ID alone may work less well. Meta suggests adding email, phone number, Facebook app user ID, Facebook Page user ID, first name or last name to support it.
How do hashing and matching protect your customer data?
Before any matching happens, the contact details in your list are hashed. Hashing is a cryptographic method that turns each identifier into a random-looking code that cannot be reversed. Meta’s page on customer lists says this is done on your own machine, before the list is sent to Meta.
Meta then compares those hashed codes with hashed information from its own profiles. When two codes are the same, that person joins your audience. Meta states that it does not learn any new identifying information about your customers from the hashed data.
Hashing does not replace your own duties. Meta asks you to review its terms and make sure you have a legal basis to use the information. Under the GDPR, the advertiser acts as the data controller for any list uploaded to create a custom audience.
How do you create a customer list custom audience?
Open Audiences in Ads Manager, select Create audience, then Custom audience, and pick Customer list. Follow the instructions to format your list, then choose how the audience can be used, upload a file or paste comma-separated values, name it, accept the custom audience terms, map your identifiers and select Import and create.
The mapping step shows a check icon when an identifier is mapped correctly and ready to be hashed. An exclamation point means you left an identifier out or one needs a manual fix. Meta says correcting these before you upload gives you a better chance of a good match rate.
You may also be asked whether your file includes a customer value column, and you can add an audience label and a description to find the audience later. Back in Audiences, the list shows Populating, then Ready once it can be used.
- Audiences: Create audience, then Custom audience
- Select Customer list, then Next
- Choose inclusions or Only exclusions
- Upload or paste, then map identifiers
- Select Import and create
What does the match score tell you?
The Match score column rates, out of ten, how well the identifiers in your last successful upload matched profiles on Meta platforms. Meta calculates it by dividing matched rows by uploaded rows, and shows it in steps of 0.5. You add it by selecting Columns in the top right of Audiences.
To raise it, Meta recommends adding more emails, phone numbers and device IDs, following its customer list formatting guidelines. The score is kept for a limited time, so if it has disappeared you may need to update your list to see it again.
Example. A shop uploads 4,000 rows with emails only and gets a middling score. It exports the same customers again with phone numbers and names, updates the list, and the score rises. Same customers, more identifiers per row.
| Signal | What it means | What to do |
|---|---|---|
| Check icon at mapping | Identifier mapped, ready to hash | Nothing |
| Exclamation point at mapping | Identifier left out or needs a fix | Correct it before upload |
| Populating | Audience is being built | Wait |
| Ready | Audience can be used in ads | Use it or build a lookalike |
| Outdated | List not updated in over 30 days | Select Update list |
| Match score | Matched rows divided by uploaded rows, out of ten | Add emails, phones, device IDs |
- Match score
- = matched rows ÷ uploaded rows
- Shown
- = out of ten, in steps of 0.5
- To raise it
- = more emails, phones, device IDs
When should you choose Only exclusions?
When you add the list, you choose between Inclusions or exclusions, and Only exclusions. The second option suits people you must always leave out, for example customers who opted out of marketing. Anyone in your ad account who tries to include that audience will find it grayed out.
The choice is final. Meta says an Only exclusions audience cannot be switched back later, and it cannot be used to make a lookalike audience. If you might want a lookalike from the same customers one day, upload a second list for that purpose.
Lists also age. If a customer list has not been updated in over 30 days, Meta marks it Outdated, which may affect your ad delivery. Use Update list to refresh it with your latest customers.
What are the access rules and limits?
You must own the ad account connected to a business portfolio, or have admin or advertiser permissions on it. A new account, or one you linked recently, may have to wait a few weeks before it can create or share a customer list custom audience. Business verification may help if the portfolio is tenured.
The audience cannot be named after, include, or be based on prohibited information. Meta lists social security numbers, health information, financial information, consumer report information and other sensitive categories defined by law or industry guidelines.
Two more limits apply. Targeting options are restricted for audiences that include people under 18, or older in some countries. And Meta warns that privacy rules in Europe may affect campaigns that advertise to people in the European Region.
How does Adwize work with your customer lists?
Adwize prepares your Meta campaigns inside your own ad account and shows you, in plain words, which audiences each ad set uses before anything goes live: a customer list, an exclusion, a lookalike or broad targeting. You approve, edit or refuse. Nothing launches without your yes. See the Launch page.
Once the campaign runs, Adwize reads the results each day. If an ad set built on a customer list costs far more than the others, it tells you in one sentence and proposes a change for your approval. See the Optimize page.
Adwize works with Meta ads only, inside your own ad account, so Meta’s rules on customer data apply exactly as they do in Ads Manager. To find new people who look like your customers, read our page on the lookalike audience.
Frequently asked questions
Does Meta see my customers’ emails in clear text?
Meta says the identifiers in a customer list are hashed on your own machine before the list is sent, and that it learns no new identifying information from hashed data. The hash cannot be reversed.
What file format does a Meta customer list use?
A CSV or TXT file holding identifiers such as emails, phone numbers and names. You can also paste comma-separated values. Meta’s formatting guidelines explain how to lay out each column.
Why is my match score low?
Usually because each row holds too few identifiers. Meta recommends adding more emails, phone numbers and device IDs. The score is matched rows divided by uploaded rows, shown out of ten.
Why can’t I create a customer list custom audience?
You need to own the ad account linked to a business portfolio, or have admin or advertiser permissions. New or recently linked accounts may wait a few weeks. Business verification may help in a tenured portfolio.
Does Adwize change my audiences without asking?
No. Adwize shows which audiences a campaign uses, proposes any change with the reason in one sentence and waits for your approval. It does not launch, change or spend anything until you say yes.
Sources
- Meta Business Help Center, About customer list custom audiencesAccessed 10/09/2026
- Meta Business Help Center, Create a customer list custom audienceAccessed 10/09/2026
- Meta Business Help Center, About customer listsAccessed 10/09/2026
