How Luma recognizes and matches songs

Library, updated October 23, 2026

Luma has no online database that recognizes songs. Everything runs on the tags in your files. Once you know which tags count, you'll understand why a song gets skipped, why an album shows up twice or why a song stays grey in a playlist.

Duplicate songs on import

Before Luma adds a song to your library, it checks two things:

• The same file: if exactly this file (in the same place) has been imported before, it isn't even copied.
• The same song: if title, artist, album, track number and length match a song in your library, it counts as already there, no matter which folder or app it comes from.

When comparing text, upper and lower case, accents (é, ü) and spaces at the start or end don't matter. The length is rounded to the full second. The file format doesn't count: a song as FLAC and the same song with the same tags and length as MP3 are one song to Luma, and the second one is skipped.

If you want to keep two versions of a song that Luma considers the same, change one of the tags before importing, for example the album name or an addition to the title.

Before a transfer with Luma Transfer

Luma Transfer uses the same comparison, just earlier: the Mac reads the tags of every file and sends this list to the iPhone first. The iPhone replies with the songs it already has, and only the rest is transferred. A song that appears twice in the same transfer also goes out only once.

If the Mac couldn't read a file's tags, the file is transferred and checked during the import on the iPhone. If it turns out to be there already, the Mac reports “Already on the device” and it takes up no space.

How albums and artists are formed

• An album is every song with the same album name and the same album artist. If a file has no album artist, the artist counts.
• An artist in your library is the album artist. That keeps songs with guest appearances (“A feat. B”) in A's album.
• Exact spelling matters here. “Abbey Road” and “Abbey road”, or “The Beatles” and “Beatles”, make two albums. The fix is in An album shows up twice: if you rename an album in Luma so that its name and album artist match an existing one, the two become one.
• Compilations need a shared album artist, such as “Various Artists”. Otherwise the compilation falls apart into many albums with one song each.

Files without tags

If tags are missing, Luma takes what the file name offers:

A number at the start only counts as a track number if it begins with zero, has a disc number in front (1-03) or is followed by a period, a bracket or a dash. “99 Luftballons” and “21 Guns” keep their names. Without an album tag, songs share the album “Unknown Album”, and each song keeps an embedded cover to itself.

Matching songs from a backup

The Luma Data backup contains no music, only the title, artist and album of every song. That goes for the songs in playlists as well as for likes and stats. When you import it, Luma looks for the matching song in your library for every entry, in this order:

1. ExactTitle, artist and album match, ignoring upper and lower case.
2. Different artistTitle and album match, only the artist is written differently, for example “JAW” instead of “JAW & Maeckes”. Punctuation and accents don't count here.
3. Without additionsTitle and album match once brackets and “feat.” are left out: “Song (feat. X)” matches “Song”, “[2002] Album” matches “Album”, “Album (Deluxe Edition)” matches “Album”.
4. Title and main artistThe title without additions and the first credited artist match, whatever the album. “Kanye West, Talib Kweli & Common” counts as “Kanye West”.

The looser steps two to four only apply when exactly one song in your library fits. If there are two candidates, for example “Masks” and “Masks (Live)” on the same album, Luma would rather match nothing than the wrong one. Length and track number from the backup play no part in matching.

Anything without a match becomes a grey entry in the playlist's Not in Library section. As soon as you import the song, Luma checks all grey entries by the same rules and puts it back in its place.

Matching likes and stats

Likes and stats are matched in the same four steps. Anything that doesn't find a song is only counted (12 songs from the backup not found) and not saved. So import the music first, then the file. For every song:

• Plays and listening time: the higher value wins, from the file or from your library. That's why importing the same file twice doesn't count anything twice.
• Several entries for one song, for example a FLAC and an MP3 version from the old library that are now one file: their plays and times are added up.
• Likes are set but never removed. Last played takes the later date, date added the earlier one.

Matching albums from collections

For collections, Luma looks for whole albums, not single songs:

1. Title and album artistBoth match, ignoring upper and lower case. If there are several such albums, the release year decides.
2. Title onlyIf you've changed the album artist since, the album title is enough, as long as it exists only once in your library.

An album Luma can't find isn't added to the collection as a grey entry, it's left out. If you read in the file again after importing the music, Luma adds it. A collection with the same name isn't created twice, it only gets the albums it's missing.

Playlists that already exist

If a playlist in the backup has the same name as an existing one (ignoring upper and lower case), Luma doesn't create it twice. Instead it adds the songs from the backup that the existing playlist is missing, at the end. Importing the same file again therefore changes nothing, and a playlist that lost songs becomes complete again. A song appears only once in any playlist.

When you change tags later

If you edit a song's title, artist or album in Luma, every playlist entry follows. A backup exported afterwards contains the new tags. An older backup with the old tags often still finds the song through the looser steps. If it doesn't, just export the backup again after tidying up.

Luma for Mac: moved and deleted files

Luma for Mac reads your music folders directly, so it also recognizes songs by the file itself:

• Moved or renamed: a file with the same name and size in a new place, or a size that occurs only once, is the same song. If it was re-tagged along the way, Luma recognizes it by title, artist, album, disc and track number. Likes, play counts and playlist positions are kept.
• Deleted: if a file is really gone, the song leaves your library. In playlists it stays as a grey entry and moves back as soon as the file reappears.
• Protection against accidents: if more than half of all songs, and more than 50, go missing at once, for example because an external drive isn't connected, Luma removes nothing.

On iPhone and iPad it's different: if you delete a song there, it also disappears from all playlists.

Still have a question or found a mistake? Email hello@suenavus.com.