Merge Two SRT Files Into One Bilingual Subtitle File
To merge two SRT files into bilingual subtitles, every cue in one language is paired with its counterpart in the other and both are written into the same cue: one line of Chinese and one of English, or Chinese with Thai or Japanese. Put the main language (A) and the second language (B) into the tool below, choose whether to pair by cue number or by overlapping time, decide whose timing wins and which language sits on top, and download one bilingual SRT. If the second language should be smaller, export ASS instead. The tool also works in reverse, splitting a bilingual SRT back into two files. Everything happens in your browser; nothing is uploaded.
- Pair by number or time
- Choose the order
- SRT or ASS
- Split back into two
Updated Nov 5, 2026Fact-checked Nov 5, 2026
episode-01.en.srt
UTF-81
00:00:00,400 --> 00:00:06,900
The champagne tower is barely up when Nora opens her eyes — she's back on the day they framed her.
2
00:00:07,100 --> 00:00:11,800
Sign the share transfer, little sister. Everyone's waiting on you.
3
00:00:12,000 --> 00:00:15,700
Sign it? Maybe look at the big screen first, Vivian.
4
00:00:15,900 --> 00:00:22,000
The lights dim. On screen, security footage — Vivian tipping powder into Nora's glass.
5
00:00:22,200 --> 00:00:25,000
Turn it off! Who told you to play that?
Merge two SRT files: add both, pick the pairing
Main language A on the left, second language B on the right. The preview shows every pair, with unmatched cues listed underneath; switch to Split to turn a bilingual SRT into two files.
How to make dual language subtitles in four steps
To merge two SRT files you need only the files themselves, no video. Before you start, settle one question: which language will the viewer actually hear?
- 01
Add the two SRT files
A is the main language, usually the one whose timing you keep; B is the second language. For a Chinese-audio version aimed at overseas viewers, A is Chinese; for an English dub, A is English.
- 02
Pick the pairing
If both files come from the same script with the same number of cues in the same order, pair by number. If they come from different sources and the counts differ, pair by overlapping time: two cues that overlap by half or more count as the same line. Two cues in B that fall inside one cue in A are merged into that cue.
Tip · Pairing by time assumes both files already match the audio; fix any overall offset first with the SRT time shift tool.
- 03
Choose the timing and the order
Keep the timing of whichever language the viewer hears, and put the viewer's own language on top. For a smaller second language, switch the output to ASS.
- 04
Check unmatched cues, then download
Cues without a partner are listed under the preview; they are usually song lyrics or on-screen text that exist in only one language. Once it looks right, download the bilingual SRT or ASS.
Combine two subtitle files: by number or by time?
Pairing is where merging two SRT files usually goes wrong. With the right method hundreds of cues line up at once; with the wrong one the whole episode ends up one line out.
By number: one script, several languages
Subtitles translated and dubbed from the same script have a fixed line-for-line match, so pairing by number is safest. That is how AI Drama Voice exports: each line of the Chinese script becomes one cue in the English, Thai and every other language's SRT, in the same order. Each language's timecodes follow its own dub, though, and English lines run longer, so the start and end times differ from the Chinese ones. An illustration:
| File | Cue 2 | Cue 3 |
|---|---|---|
| Chinese SRT | 00:00:04,470 --> 00:00:07,060 · 妹妹，这份股权转让书签了吧。 | 00:00:07,410 --> 00:00:09,880 · 签？姐姐不如先看看大屏幕。 |
| English SRT | 00:00:04,980 --> 00:00:08,310 · Sign the share transfer, little sister. | 00:00:08,660 --> 00:00:11,540 · Sign it? Maybe look at the big screen first. |
| Merged (English timing, English on top) | 00:00:04,980 --> 00:00:08,310 · Sign the share transfer, little sister. / 妹妹，这份股权转让书签了吧。 | 00:00:08,660 --> 00:00:11,540 · Sign it? Maybe look at the big screen first. / 签？姐姐不如先看看大屏幕。 |
Regenerate failed lines first
The export includes only lines that were generated successfully. If one line failed in one language and wasn't retried, that language's SRT is one cue short and pairing by number slips from that point. Regenerate it in My dubbing projects, then export.
By time: subtitles from different sources
When the Chinese subtitles come from one place and the English from another, the line breaks and cue counts differ and the numbers mean nothing; only timing helps. A cue in A and a cue in B that overlap by half or more are treated as the same line. If B is cut finer, one Chinese cue often meets two English ones: 签？姐姐不如先看看大屏幕。 against "Sign it?" and "Maybe look at the big screen first." The tool merges both English cues into the one Chinese cue. Cues with no counterpart on either side are listed so you can delete them or keep them in one language.
Whose timing to keep
| The video you're making | Use the timing of | Why |
|---|---|---|
| English dub for overseas viewers | English (the dub) | Subtitles should appear and disappear with the English voice |
| Chinese audio with English for overseas viewers | Chinese (the original) | The voice is Chinese; the English is a translation riding on its rhythm |
| Thai dub with Chinese underneath for review | Thai | The reviewer hears the Thai dub; the Chinese is only a content check |
Bilingual subtitles generator settings: order, size and splitting
Laying out dual language subtitles comes down to two decisions: which language goes on top, and whether the second one should be smaller.
- Order: put the viewer's own language on top, where the eye lands first. Chinese viewers watching a foreign film get Chinese on top; overseas viewers watching a dub get the dub language on top and Chinese below.
- Lines: every bilingual cue has at least two lines. If a sentence already wraps onto two lines, the cue grows to three or four and covers a big part of a vertical frame. Shorten long lines with the subtitle line length checker before merging.
- Size: SRT is essentially plain text, and players treat tags such as <font size> inconsistently, so two sizes are hard to get. For a smaller second language, export ASS, which carries a style sheet that players such as PotPlayer and VLC follow.
- In an editor: you can also skip merging and import the two single-language SRT files as two caption tracks, each with its own size and position.
Split a bilingual SRT back into two files
Merging works in reverse too. If you have a bilingual SRT and need only one language, switch to Split. Split by line sends each cue's first line to one file and the second to the other; split by Chinese characters sends lines containing Chinese to one file and the rest to the other, judging mixed lines by the share of Chinese characters.
| The bilingual file | Split by | Why |
|---|---|---|
| Always two lines: Chinese above, English below | Line | A regular layout splits most accurately by position |
| Some cues have two Chinese lines and one English | Chinese characters | Line counts vary, so splitting by position would push Chinese into the English file |
| Chinese and Japanese | Line | Japanese uses Chinese characters too, so a character rule would file it as Chinese |
Beyond Chinese and English: Thai, Vietnamese, Japanese and Korean
The tool doesn't care about language: you can merge two SRT files in any pair of languages. These are the issues that come up most with the languages our dubbing covers.
Thai · ไทย
Thai + Chinese
Thai puts no spaces between words, so a sentence looks like one long string and line wrapping is left to the software. Preview the merged file on a phone to make sure the Thai doesn't break in odd places.
- Boxes mean the font lacks Thai; switch fonts
- Keep the Thai dub's timing
Vietnamese · Tiếng Việt
Vietnamese + Chinese
Vietnamese uses Latin letters with tone marks, sometimes two stacked on one letter. At small sizes the marks blur, so don't shrink Vietnamese too far when it is the second language.
- Choose a font with full Vietnamese tone-mark support
- Vietnamese lines usually run longer than Chinese
Japanese · 日本語
Japanese + Chinese
Japanese mixes Chinese characters with kana, and next to Chinese the two are easy to confuse. Use a different colour or size for each line, and split by line.
- Split by line, never by Chinese characters
- A Japanese dub keeps the Japanese timing
Korean · 한국어
Korean + Chinese
Korean puts spaces between word groups, so long lines can break at a space. Missing glyphs also show as boxes, so check on the target device before export.
- Switch to a font that covers Hangul
- A Korean dub keeps the Korean timing
Merging the SRT files from a dub: five practical habits
AI Drama Voice exports SRT files for Chinese plus eight foreign languages from one script, cue for cue, which is the ideal case when you merge two SRT files by number.
Export every language at once
After generation, click All languages (ZIP): each language's MP3 and SRT are inside, and the language code in the file name keeps A and B from getting mixed up.
Make the dub language A
For an English dub, put the English SRT in A and keep A's timing, with Chinese in B as the reference; the subtitles then follow the English voice.
Keep review and release versions apart
Review with the foreign language on top and Chinese below to check content; for release to overseas viewers, a single-language subtitle is usually all you need.
Change one line, replace both
When a line is re-dubbed, download that language's SRT again and merge again, or the two languages in the bilingual file will drift apart.
Check it in CapCut
Import the bilingual SRT with the matching MP3 into CapCut and see how many lines each cue takes in a 9:16 frame; the steps are in the CapCut sync guide.
Frequently asked questions
Put the main language in A and the second in B, pair by number if both come from the same script or by overlapping time if they don't, choose whose timing to keep and which language goes on top, and download. It all runs in your browser with no upload.
Pair by overlapping time: cues that overlap by half or more count as the same line, one-to-many matches are merged automatically, and whatever stays unmatched is listed for you to delete or keep. Make sure both files are in sync with the audio first.
The language the viewer hears: a dub uses the dub language's timing, an original-audio video uses the original language's. For silent review, use the language being reviewed.
Yes. A bilingual SRT is simply a file whose cues have two lines of text, so it imports like any SRT, with both languages sharing one style. For different sizes, import the two single-language SRT files as two caption tracks and style each one.
Yes. Switch to Split and choose by line (first line to one file, second to the other) or by Chinese characters. Fixed two-line cues split best by line; Chinese-Japanese files must be split by line, since Japanese uses Chinese characters as well.
Yes. The tool works with any pair of SRT files, and AI Drama Voice can dub a Chinese script into Thai, Vietnamese and six more languages with an SRT for each. If Thai or Vietnamese shows as boxes, switch to a font that covers the language.
Let the same cast voice the other half of your subtitles One script, every language lined up.
Paste a Chinese episode, pick English, Thai, Vietnamese or more, and AI voices every line and exports an SRT per language, ready to merge by number. Cast analysis is free.
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