Merge SRT Files Into Dual Subtitles
Merge SRT files in two languages into one dual-subtitle file, so both show at once in any player. Stack them at the bottom, or put one language at the bottom and the other at the top in a second colour. Lines that start a little apart are matched automatically. Your subtitles stay on your device; nothing is uploaded.
- Runs on your device
- Browser APIs
- Works offline
Updated
Drop your subtitle files here
How to merge two subtitle files into one
Step 1: Drop exactly two subtitle files on the box above, one per language. They should belong to the same video version.
Step 2: Drag them into order: the first file is the main language.
Step 3: Choose a Layout and Save as ASS (colours and top/bottom placement) or SRT (plays everywhere).
Step 4: Press Merge and download the dual subtitles file.
Good to know
Settings explained
- Save as
- Top/bottom placement and different colours need ASS.
- Match lines within
- Lines starting this close together are shown together.
Formats
Combines 2 or more files into one result.
How it runs
- Built-in browser features
- Uses standard browser features only — nothing extra to download.
Stacked or top and bottom, SRT or ASS
ASS gives the cleanest bilingual subtitles: two styles, two colours, two positions. SRT has no colours or styles, but nearly every player and TV reads it.
| Save as ASS (default) | Save as SRT | |
|---|---|---|
| Stacked at bottom | First language above, second below in the colour you pick | Both languages in one block, same colour |
| One top, one bottom | First at the bottom; second at the top, slightly smaller, in your colour | Second language tagged {\an8}; shows on top where the player supports it |
| Best player support | VLC, mpv, MPC-HC, Kodi, Plex | Almost every player and TV |
What are dual subtitles?
Dual subtitles (also called bilingual or double subtitles) show the same line in two languages at once, for example Spanish with English underneath. Streaming sites offer them through browser extensions; for your own video files you need one subtitle file that contains both languages, because most players show only one subtitle track at a time.
Language learners use them to read the original and check the meaning without pausing. Couples and families who share a screen use them so everyone can follow.
How the two timelines are combined
Translations are rarely timed identically. When lines in the second file start or end within the Match lines within window (300 ms by default, adjustable from 0 to 1000 ms under Advanced settings), they snap to the first file’s times and appear together.
In the stacked layout, the merged timeline is cut into segments wherever either language changes, so a long line in one file stays on screen while two shorter lines in the other replace each other underneath.
How to show two subtitles at once in VLC or mpv
VLC 3 shows one subtitle track at a time, so the dependable method is a merged file: load the result with Subtitle → Add Subtitle File, or give it the same name as the video. mpv can display a second track itself with its --secondary-sid option, but a merged ASS file is easier to share and also works on TVs with Kodi or Plex.
Tips & troubleshooting
The two files drift apart? Line them up first with subtitle sync, then merge.
Only have one language? Translate subtitles to make the second file, keeping the same timing.
Want both languages on a video for social media? Burn subtitles into video using the merged ASS file.
Want the merged file inside an MP4 or MKV as a track viewers can switch off? Add subtitles to video puts it there, usually without re-encoding the picture.
Sound tags like [MUSIC] crowding the screen? Run both files through the SRT cleaner before merging.
Dual Subtitles (Merge Two Languages) FAQ
How do I merge SRT files into one?
Drop two SRT files here, drag the main language first, pick a layout and press Merge. The result is one file with both languages on the same timeline. VTT, ASS and other text formats work as input too.
Can I join part 1 and part 2 (CD1 and CD2) subtitles?
Not with this tool. It overlays two languages for the same video; it does not append one file after another. To join parts, shift the second file by the length of part 1 with subtitle sync and paste its lines into the first in a text editor.
How do I make bilingual subtitles?
Get a subtitle file for each language for the same version of the video, merge them here and save as ASS. Players such as VLC, mpv and Kodi then show both languages, each in its own colour.
Why do the two languages not line up?
The files were probably made for different releases. Lines that start within 300 ms are matched automatically; for anything larger, sync the second file to the first, or raise Match lines within to as much as one second.
Are your subtitle files uploaded anywhere?
No. Your subtitle files are processed by your own browser on your own device. There is no server that receives files, so nothing is uploaded, stored or shared. You can even switch to airplane mode once the page has loaded.