How to Add Custom Subtitles to Plex

How to Add External Subtitles to Plex Media Server

Plex is excellent at organizing your media library, but sometimes it does not automatically find the right subtitles. This is especially common when you have translated subtitles yourself using SubWiz, because Plex has no way to discover files that do not follow its strict naming rules.

Here is the complete guide to getting external subtitles recognized and playing in Plex.

How Does Plex Detect External Subtitle Files?

Plex uses strict filename matching to detect external subtitle files. It does not look at the content of the file or try to guess the language. If the filename does not follow the exact convention, Plex ignores the file completely.

The naming pattern is:

Movie_Name (Year).Language_Code.ext

For TV shows, the pattern is:

Show_Name S01E01.Language_Code.ext

The language code uses ISO 639-1 codes, which are two-letter abbreviations. This tells Plex what language the subtitle is in so it can display the correct label in the subtitle picker.

Examples for Movies

• Movie file: Avatar (2009).mp4
• Subtitle file: Avatar (2009).es.srt for Spanish
• Subtitle file: Avatar (2009).en.srt for English
• Subtitle file: Avatar (2009).fr.srt for French

Examples for TV Shows

• Episode file: Breaking Bad S01E01.mp4
• Subtitle file: Breaking Bad S01E01.es.srt for Spanish
• Subtitle file: Breaking Bad S01E01.pt-BR.srt for Brazilian Portuguese

The subtitle file must be in the same folder as the video file. Plex does not search subdirectories for external subtitles.

What Language Codes Does Plex Accept?

Plex uses ISO 639-1 two-letter language codes. Here are the most common ones:

• English: en
• Spanish: es
• French: fr
• German: de
• Portuguese: pt
• Brazilian Portuguese: pt-BR
• Italian: it
• Japanese: ja
• Korean: ko
• Chinese: zh
• Russian: ru
• Arabic: ar
• Hindi: hi
• Dutch: nl
• Swedish: sv

For regional variants like Brazilian Portuguese or Traditional Chinese, include the region code after a hyphen. Without the region code, Plex just labels it as the base language.

You can also add a forced flag by appending .forced to the filename, like Avatar (2009).en.forced.srt. This tells Plex to always display these subtitles, which is useful for scenes where characters speak a foreign language.

How Do I Add Subtitles to Plex Step by Step?

Once your files are named correctly, here is how to get them recognized by Plex.

1. Rename your subtitle file following the naming convention above. Double-check the video filename matches exactly, including spaces and punctuation.

2. Place the subtitle file in the same folder as the video file. This is required. A separate subtitles folder will not work.

3. Open the Plex Web App in your browser.

4. Go to the library containing the movie or show.

5. Click the three dots next to the library name and select Scan Library Files. This triggers a deeper scan that picks up new external files.

6. Wait for the scan to finish. For large libraries, this can take several minutes.

7. Click on the movie poster to open the details page.

8. Look for the Subtitles dropdown, usually near the Audio settings on the details page.

9. You should see your new subtitle listed, for example "Spanish (External)" or "French (External)".

10. Select it and hit play. The subtitle should display during playback.

If you have subtitles in multiple languages, they will all appear in this dropdown. Each language is listed separately so you can switch between them.

Why Are My Subtitles Not Showing Up in Plex?

This is the most common issue people run into. Here are the causes and fixes, in order of how often I see them.

The filename does not match. Plex is case-sensitive on Linux systems and can be picky about spaces. If your video is Avatar (2009).mp4 but your subtitle is avatar (2009).es.srt, it may not be detected on some systems. Match the filename exactly.

The language code is wrong. Using english instead of en or spanish instead of es will cause Plex to ignore the file. Use two-letter ISO codes only.

The files are in different folders. The subtitle must be in the same directory as the video. A Subs or Subtitles subfolder will not work for external subtitle detection in Plex.

The library was not rescanned. After adding subtitle files, you need to trigger a scan. Use "Scan Library Files" rather than just "Scan Library" because the former does a deeper scan that picks up new external files.

Local Media Assets is disabled. Plex needs the Local Media Assets agent to detect external subtitles. Go to Settings, Agents, Movies, and make sure Local Media Assets is checked in the list. For TV shows, check under Agents, Shows.

The file extension is wrong. Plex supports .srt, .vtt, .ass, .ssa, and .sub. If your file has a different extension or a double extension like .srt.txt, rename it.

How Do I Add Subtitles to TV Shows in Plex?

TV shows follow the same naming rules but with the SXXEXX episode format.

For a show stored as:

• /TV Shows/Breaking Bad/Season 01/Breaking Bad S01E01.mp4

Your subtitle should be:

• /TV Shows/Breaking Bad/Season 01/Breaking Bad S01E01.es.srt

The episode identifier (S01E01) must match exactly. If the video uses dots instead of spaces, like Breaking.Bad.S01E01.mp4, the subtitle should match: Breaking.Bad.S01E01.es.srt.

For entire seasons at once, place each subtitle file in the corresponding Season folder. Plex scans each episode individually, so every subtitle file needs its own correctly named entry.

Can I Use VTT Files with Plex?

Yes. Plex supports VTT (WebVTT) files alongside SRT. Use the same naming convention, just change the extension:

• Avatar (2009).es.vtt for Spanish
• Breaking Bad S01E01.en.vtt for English

VTT works well on the Plex web player and most modern clients. SRT has slightly broader compatibility across older devices and TV apps, so when in doubt, use SRT.

Both formats can coexist for the same video. You can have Avatar (2009).es.srt and Avatar (2009).fr.vtt in the same folder, and Plex will detect both.

How Do I Set a Default Subtitle Language in Plex?

Plex lets you configure default subtitle behavior so you do not have to select subtitles manually every time.

1. Go to Settings in the Plex Web App.

2. Select the user account you want to configure.

3. Under Playback, look for Subtitle settings.

4. You can set:

   • A preferred subtitle language that auto-selects when available
   • Whether to show subtitles by default
   • Whether to prefer forced subtitles for foreign language sections

This applies to all videos in your library. If a matching subtitle file exists, Plex will select it automatically when you start playback.

What About Embedded Subtitles vs External Subtitles?

Videos can have subtitles embedded inside the file (often in MKV containers) or stored as external files. Plex handles both, but they behave differently.

Embedded subtitles are part of the video file and do not require separate files. They show up automatically in the subtitle list. The downside is that you cannot easily edit or replace them without re-encoding the video.

External subtitles are separate files sitting next to the video. You can add, remove, or replace them without touching the video file. This is the better approach if you are translating subtitles with SubWiz, because you can generate new files and drop them in without re-encoding anything.

Related Articles

• Jellyfin subtitle guide
• Kodi subtitle guide

Summary

Getting subtitles into Plex comes down to three things. Name the file correctly using the Filename.LanguageCode.srt pattern. Put it in the same folder as the video. Scan the library files after adding it. If subtitles still do not appear, check that Local Media Assets is enabled and the language code is a valid two-letter ISO code.

Need high-quality subtitles for your Plex library? Translate them instantly with SubWiz.