Customer List Formatter for Reddit Ads Custom Audiences

How to make a Reddit Ads custom audience file

A Reddit ads custom audience from your customer list has one detail that trips people up: Reddit cleans emails differently from Google and Meta. Before hashing, it removes the +alias and every dot or symbol from the name part of every address, as its advanced matching guide explains. A list hashed with another platform's rules usually keeps those dots, so its hashes differ and fewer people match. This tool applies Reddit's steps, hashes on your device and fills Reddit's custom audience template.

1. Add your export. Shopify, a subscription platform, a CRM or an app database. Try sample data includes Reddit's own example address.
2. Map the columns. Pick the email columns, the mobile ad ID column and, if you have one, the device or platform column.
3. Choose hashed or unhashed emails. Hashed applies Reddit's cleanup first. Unhashed sends the addresses as they are, and Reddit hashes them on upload.
4. Check the ad IDs. Android IDs are lowercased and Apple IDs uppercased, using the device column or the type you pick.
5. Download the CSV. It has Reddit's three headers, one value per row, and no empty rows.

One customer, three spellings

Your shop may hold [email protected] from an order and [email protected] from a newsletter form. After Reddit's cleanup both are [email protected], one hash. The tool removes such duplicates, so the row count you see is the number of real people.

Upload the list in Reddit Ads

1. Open Audience Manager and click New Audience › Custom audience.
2. Choose customers list and give the audience a name.
3. Pick Upload a File and select the CSV, or Copy & Paste with the header line included and one value per line.
4. Read and agree to the terms, then click Save.
5. Stay on the page until you see “Audience upload completed successfully”. Then check back: orange means processing, green means ready.

If you hashed emails and also have ad IDs, upload the second file as its own list. Reddit partners such as LiveRamp can push lists for you instead; their minimum is 25 matches, with 4 to 6 days of processing.

Reddit custom audience errors and fixes

Upload error after editing the template

Reddit says not to change or remove the column headings. “Email” instead of “Emails (unhashed)”, or a deleted MAID column, is enough to fail. Our file always carries the three original headings.

Reddit custom audience too small

Red status means an error, and an audience that is too small is the example Reddit gives: it needs at least 1,000 matches. Reddit also wants at least 1,000 rows in the file. Since only people with a Reddit account match, start with several thousand customers if you can.

Hashed and unhashed emails in one file

Reddit's rule: an import has either prehashed emails, or unhashed emails and MAIDs. Mixing a prehashed column with unhashed emails breaks that rule, so the tool writes hashed emails and ad IDs to separate files.

IDFA in lower case, AAID in capitals

Reddit's ad IDs are case-sensitive: Android AAIDs lowercase, Apple IDFAs uppercase. Exports do not always follow that. Map the device column, or tell the tool what kind of IDs you have. The all-zero ID is invalid and is removed.

Browser freezes during upload

Reddit suggests another browser or a smaller file. Delete empty rows first; this tool never writes any. Files over 500 MB, or over 1 million rows, are split for you.

Campaigns in Europe

Reddit notes that European privacy changes may affect campaigns that target users in Europe. Check Reddit's current guidance before you build a list for European targeting.