Merge Subtitles

Combine Two Subtitle Files Into One

Merge two subtitle files to create bilingual subtitles, combine primary and foreign language captions, or join multi-part subtitle files. Perfect for language learning, accessibility, and multi-file video projects. Supports SRT, ASS, SSA, and VTT formats with multiple merge modes and customizable colors.

How to Merge Subtitle Files

Merging subtitles combines two subtitle files into a single file:

1. Select your base subtitle file - This is your primary subtitle file. The merged result will use this file's format and structure. Click "Browse..." under "Base file" to upload it.
2. Select your merge subtitle file - This is the secondary subtitle file you want to combine with the base. Click "Browse..." under "Merge file" to upload it.
3. Choose a merge mode - Select how the two subtitle files should be combined: Simple (default), Top and bottom (split screen), Nearest cue (sync similar timing), or Glue (attach end-to-end).
4. Optional: Add colors - Check the color boxes and select different colors for each subtitle to make them easily distinguishable on screen.
5. Click Merge - Process the files and download your merged subtitle file instantly.

Understanding Merge Modes

This tool offers four different merge modes to handle various subtitle merging scenarios:

Simple Merge (Recommended for Dual Language)

The simple merge mode combines all subtitle entries (cues) from both files into a single file. Each subtitle appears at its original timing, and both languages display simultaneously when their timings overlap. This is the most common mode for creating bilingual subtitles for language learning.

Best for: Dual-language subtitles where you want to see English and Spanish (or any two languages) on screen at the same time.

Top and Bottom of Screen

Similar to simple merge, but adds positioning styling so one subtitle appears at the top of the screen and the other at the bottom. The base file subtitles appear at the bottom (standard position), while merge file subtitles appear at the top. This creates clear visual separation between the two subtitle tracks.

Best for: Language learners who want clear visual distinction between native language (bottom) and target language (top).

Nearest Cue (Smart Sync)

This intelligent merge mode looks for subtitle entries with similar timing in both files. You set a threshold (in milliseconds). If a subtitle from the merge file appears within the threshold of a subtitle from the base file, they're combined into one subtitle entry. If no matching timing is found, the merge subtitle is added as a separate entry.

The default threshold is 1000ms (1 second). This means if a Spanish subtitle appears within 1 second of an English subtitle, they'll be merged together instead of appearing separately.

Best for: Combining two translations of the same content where the timing isn't perfectly synchronized, but close enough to pair together.

Glue Subtitles End-to-End

This unique mode concatenates subtitle files sequentially rather than combining them by timing. The merge file's subtitles are attached to the end of the base file's subtitles. All timing in the merge file is shifted forward so it starts after the last subtitle of the base file finishes.

The glue offset (default 1000ms) controls the gap between the last subtitle of the base file and the first subtitle of the merge file.

Best for: Old multi-CD movies or TV shows where you have separate subtitle files for each disc/part but your video file is combined into one file. Also useful for concatenating episodes.

Note: Glued subtitles often need manual sync adjustment afterward using our Partial Shifter tool to perfect the timing for the second part.

Why Merge Subtitle Files?

Language Learning

The most popular use case. Merge native language subtitles with target language subtitles to see both simultaneously. For example, combine English and Spanish subtitles to learn Spanish while understanding the context. This immersive approach helps you connect words and phrases between languages naturally.

Fix Missing Foreign Language Subtitles

Many subtitle files assume certain dialogue is "burned in" to the video (hard-coded foreign language text). If you're watching a version without these hard-coded subtitles, parts of the dialogue are missing. Merge a foreign language subtitle file to fill in these gaps. Common in international films where characters switch between languages.

Combine Multi-Part Subtitle Files

Old movie releases were split across multiple CDs (CD1, CD2), each with its own subtitle file. If you've combined those video files into one file, you need to glue the subtitle files together to match. The glue mode is specifically designed for this scenario.

Create Accessibility-Enhanced Subtitles

Combine standard dialogue subtitles with sound effect descriptions (SDH - Subtitles for the Deaf and Hard of hearing) to create a more comprehensive viewing experience. Merge regular subtitles with a file containing [door slams], [music playing], etc.

Common Use Cases

1. Spanish Language Learning (English + Spanish)

Download English subtitles (base file) and Spanish subtitles (merge file) for a Spanish TV series. Use Simple merge mode. Enable colors: make Spanish subtitles yellow and English subtitles white. Now you can watch with both languages displayed, reading Spanish first and checking English for context when needed.

2. Movies with Foreign Language Dialogue

You're watching an English-language war movie that has scenes with German dialogue. The English subtitle file has gaps during German dialogue (assuming burned-in German subtitles). Download English subtitles (base) and German-to-English subtitles (merge). Use Simple merge to combine them, so all dialogue is subtitled.

3. Two-Part Movie with Combined Video

You have a long movie that was originally split as "Movie-CD1.avi" and "Movie-CD2.avi", now combined into "Movie-Complete.mkv". You have separate subtitle files: "Movie-CD1.srt" and "Movie-CD2.srt". Use Glue end-to-end mode with CD1 subs as base and CD2 subs as merge. Adjust glue offset if there's a gap or overlap between parts.

4. Anime with Romaji and English

Merge Japanese romaji subtitles (romanized Japanese text) with English translations. Use Top and Bottom mode: romaji on top, English on bottom. Language learners can read the pronunciation while seeing the English meaning simultaneously.

Using Subtitle Colors Effectively

When merging two subtitle files, using different colors for each helps distinguish them visually:

• Check "Color the base subtitle file" and pick a color (default: orange). This colors your primary language subtitles.
• Check "Color the merge subtitle file" and pick a contrasting color (default: blue). This colors your secondary language subtitles.
• High-contrast color pairs work best: Yellow + Cyan, White + Orange, Green + Magenta, etc.
• Keep accessibility in mind: Avoid red-green combinations (difficult for colorblind viewers). Yellow and cyan are universally readable.
• Test on your player: Not all media players support colored subtitles. VLC and MPC-HC work well. Smart TVs may ignore colors.

Tips for Perfect Merged Subtitles

• Use the same video source for both subtitle files - Subtitles synced to different video releases (BluRay vs Web-DL) may have different timings, causing sync issues when merged.
• Test in short clips first - If merging long movies (2+ hours), test your merge settings on a 5-minute sample first to ensure the result looks correct.
• Check subtitle overlap - If both subtitles appear at exactly the same time frequently, they may stack vertically and be hard to read. Using colors helps distinguish them.
• Base file format is preserved - The merged result will be in the same format as your base file (SRT, ASS, etc.). If you need ASS format for advanced styling, make sure your base file is ASS.
• Adjust threshold for nearest cue mode - If subtitles aren't pairing correctly, increase the threshold from 1000ms to 2000ms or 3000ms. If too many unrelated subtitles are pairing, decrease it to 500ms.
• Manually fix glued subtitles - After using glue mode, the second part often needs timing adjustment. Use our Partial Shifter to fix second-part sync.

Troubleshooting Common Issues

Issue 1: Subtitles Are Out of Sync After Merging

Cause: Your two subtitle files were synced to different video versions (different releases, runtimes, or cuts of the same movie). When merged, one or both subtitle tracks don't match your video's timing.

Solution: Before merging, sync each subtitle file individually to your video using our Subtitle Shifter. Once both are synced to your specific video, then merge them. Alternatively, find subtitle files designed for the same video release.

Issue 2: Only One Language Appears (Second Language Missing)

Cause: Your video player may not support styled or merged subtitles properly. Some basic players only display the first subtitle track or strip styling.

Solution: Try playing the merged subtitle file in VLC Media Player, MPC-HC, or PotPlayer, which have excellent subtitle support. If you're using a TV or streaming device, these often have limited subtitle features. Play the file on a PC instead for full dual-subtitle support.

Issue 3: Subtitles Overlap and Are Unreadable

Cause: Both subtitle files have entries at the exact same timing, causing them to stack vertically in the same screen area. Without color differentiation or positioning, they blend together.

Solution: Use the "Top and Bottom of screen" merge mode to position subtitles separately. Additionally, enable colors for both base and merge files with highly contrasting colors (yellow + cyan, white + orange). Test in VLC to see if the separation works. If your player doesn't support top positioning, colors alone should help distinguish the subtitles.

Advanced Merging Techniques

Creating Three-Language Subtitles

While this tool merges two files at once, you can create three-language subtitles by merging twice. First, merge Language A (base) + Language B (merge) to create "A+B.srt". Then merge "A+B.srt" (base) + Language C (merge) to create "A+B+C.srt". Use different colors for each language to distinguish them.

Merging Dialogue with Sound Effects

Some subtitle files only contain dialogue, while others contain sound effect descriptions ([door opens], [suspenseful music], etc.). Merge dialogue subtitles (base) with sound effect subtitles (merge) using Simple mode to create comprehensive subtitles that include both dialogue and audio cues. Very useful for accessibility.

Fixing Multi-CD Movies Permanently

If you've glued CD1 and CD2 subtitles but the second part is out of sync, use this workflow: Glue the subtitles first. Play the merged file and note exactly when the second part starts in your video (e.g., 54 minutes 30 seconds) and how much the subtitle timing is off (e.g., 2 seconds early). Then use our Partial Shifter to shift only the second part forward by 2000ms, starting from 54:30. This creates perfectly synced subtitles for your complete movie file.

Related Tools

• Subtitle Shifter - Sync subtitle timing before merging to ensure both tracks match your video
• Partial Shifter - Fix timing for glued multi-part subtitles by shifting only part of the file
• Change Color - Color individual subtitle files before merging for maximum compatibility
• Format Converter - Convert subtitle formats if your base and merge files are incompatible
• All Subtitle Tools - Browse our complete collection of subtitle editing tools

Frequently Asked Questions

Can I merge subtitles in different formats (SRT + ASS)?

Yes, you can merge different subtitle formats. However, the output file will match the format of your base file. If your base is SRT and merge is ASS, the result will be SRT (ASS styling may be lost). For best results, convert both files to the same format before merging using our format converter.

Which merge mode should I use for language learning?

Use "Simple merge" for language learning. It displays both languages simultaneously when they appear on screen. Optionally use "Top and Bottom" if your player supports it for better visual separation. Enable colors with contrasting colors (e.g., target language in white, native language in yellow) to easily distinguish them while watching.

Will merged subtitles work on my TV or streaming device?

It depends on your device. Most modern smart TVs can display merged subtitles, but may ignore color and positioning styling. They'll show both subtitle tracks, but possibly in plain white at the bottom. For best results with colors and positioning, use a computer with VLC, MPC-HC, or PotPlayer. Streaming devices like Roku or Fire TV have limited subtitle support.

My merged subtitles are out of sync. What went wrong?

The most common cause is that your two subtitle files were synced to different video versions (BluRay vs Web-DL, Extended vs Theatrical, different frame rates). Before merging, individually sync each subtitle file to your specific video using our Subtitle Shifter. Once both are synced, merge them. The merged result will stay in sync because both tracks match your video timing.

Can I undo a merge or separate the subtitles later?

No, once merged, the two subtitle files become one. There's no automatic way to separate them. Always keep your original unmerged subtitle files as backups. If you need to make changes, go back to the original files and merge again with different settings.