How does bilingual mode align cues?

Bilingual mode finds cues with overlapping time ranges between the two files. For each primary cue, it identifies the secondary cue(s) that share the same timing window and combines their text. Non-overlapping cues are included individually.

Can I control which file's cues appear first in bilingual mode?

Yes. The order setting lets you choose whether the primary file's text appears first or the secondary file's text appears first within each combined cue. This determines the reading order for bilingual display.

What happens when cues overlap partially in bilingual mode?

When cues from the two files partially overlap in time, the merger creates combined cues for the overlapping portion and individual cues for non-overlapping portions. This preserves all subtitle content while maintaining timing accuracy.

Does the merger renumber SRT cues automatically?

Yes. In both modes, the output SRT file has cues renumbered sequentially starting from 1. This ensures valid SRT structure regardless of how the input files were numbered.

Can I merge more than two subtitle files?

This tool merges two files at a time. For three or more files, merge the first two, then use the output as input for the next merge. Repeat until all files are combined.

What output format should I choose?

SRT is the most compatible output format. VTT is preferred for web video and browsers. ASS preserves more styling but is less universally supported. Choose based on your target playback platform.

Absolutely. All processing happens client-side in your browser. No subtitle files are ever uploaded to a server.

How does the merger handle different frame rates between files?

The merger works with millisecond timestamps internally, so files with different frame rates can be merged. Timestamps are preserved as-is from each input file, maintaining their original precision.

Can I merge subtitle files from different video releases?

You can, but results may be poor if the timing differs significantly between releases. For best results, ensure both subtitle files are from the same video version. Sequential mode is more tolerant of timing differences than bilingual mode.

Does the merger support RTL (right-to-left) languages?

Yes. The merger preserves UTF-8 encoding and text content. RTL languages like Arabic and Hebrew display correctly in the output. Note that cue display direction depends on your video player's settings.

What if both files have exactly the same content?

In bilingual mode, you would get duplicate text per cue (original + identical copy). In sequential mode, you would get the subtitles played twice in sequence. This is unusual but technically valid output.

Can I use the merged file for DVD or Blu-ray authoring?

The merged output is a standard subtitle file. For DVD or Blu-ray authoring, you may need to convert it to the appropriate format (VOBSUB for DVD, PGS for Blu-ray) using your authoring software.

How large is the merged file?

The merged file is roughly the sum of both input files' sizes. In bilingual mode, it may be slightly larger due to combined cue text. In sequential mode, it is approximately the sum of both files since all cues from both are preserved.

Can I merge subtitles online without installing software?

Yes. This browser-based subtitle merger works online on Windows, macOS, Linux, Android, and iOS. The files are processed locally and are never uploaded. For cues that must stay in two visible languages, the dedicated [bilingual merger](/bilingual-merger/) gives you more alignment control.

Which tool should I use to combine or repack subtitle parts?

Use this merger to join Part 1 and Part 2 into one continuous timeline. Use the [subtitle splitter](/subtitle-splitter/) when you need to break a long file back into sections, and the [subtitle editor](/subtitle-editor/) to check text and timing after the merge.

Subtitle Merger

Combine two subtitle files into one bilingual subtitle or merge them end-to-end. Perfect for dual-language subtitles and episode combining.

Drag & drop your subtitle file here

Drag and drop subtitle files here or click to browse

SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT, JSON

Browser-Based Processing · Files Stay on Device

Core Processing Architecture

Key Features

Engineered for video editors and localization teams. Helps enforce common subtitle timing rules and formatting.

Combine two subtitle files into one in bilingual mode (dual-language) or sequential mode (append)

Bilingual mode aligns cues by overlapping time ranges for side-by-side language display

Sequential mode concatenates files with an automatic timecode offset for continuous playback

Control gap behavior between sequential cues: no gap, blank line, or custom separator

Supports SRT, VTT, ASS, SSA, LRC, and SBV input formats in any combination

Flexible cue ordering: primary file first or secondary file first in bilingual output

Automatic re-numbering of sequential cues for valid output structure

Browser-based processing, no file uploads, files stay on your device

Live Preview & Execution Pipeline

Subtitle Merger Live Execution Demo

en_dialogue.srt

READYTrack 1

00:01.000Welcome to the presentation.

00:05.200Let us begin with chapter one.

zh_dialogue.srt

READYTrack 2

00:01.000欢迎来到演讲现场。

00:05.200让我们从第一章开始。

bilingual.srt

READYBilingual

01.000ENWelcome to the presentation.
01.000ZH欢迎来到演讲现场。
05.200ENLet us begin with chapter one.
05.200ZH让我们从第一章开始。

In-Memory Processing

File parsing, mutations, and time shifts for standard tools run in browser memory without sending subtitle files to our servers.

Millisecond Precision

Millisecond-accurate timecode parsing and arithmetic prevent synchronization drift across desktop and web players.

Fault-Tolerant Engine

Automatic multi-encoding detection and syntax sanitization gracefully handle malformed cues and unexpected linebreaks.

Production Workflows

Common Use Cases

Real-world scenarios across video post-production, course transcription, and global localization.

SCENARIO #1

Multi-Part Video Subtitles

Combine subtitle files from a multi-part video (Part 1 and Part 2) into a single continuous subtitle file using sequential mode with automatic timecode offset.

SCENARIO #2

Bilingual Display

Merge original and translated subtitle tracks into a single bilingual file using bilingual mode, showing both languages per cue for viewers who need both.

SCENARIO #3

Split Video Reassembly

If a video was split into segments for editing, merge the individual subtitle files back into one continuous file for the reassembled video.

SCENARIO #4

Subtitle Track Combination

Combine a regular subtitle track with an SDH (Subtitles for Deaf and Hard of Hearing) track, or merge primary dialogue with secondary commentary subtitles.

SCENARIO #5

Episode Compilation

Merge subtitle files from TV episodes into a single file for a compilation or marathon cut, with proper sequential timing offsets for each episode.

SCENARIO #6

Bilingual Subtitle Workflow

Translate one subtitle track, then align the original and translated tracks cue by cue to produce a readable bilingual subtitle for language learning.

Execution Pipeline

How It Works

Streamlined end-to-end processing pipeline engineered for speed and precision.

STEP 01

Upload & Import

Select your first subtitle file (primary track).

PHASE 01

STEP 02

Format Analysis

Select your second subtitle file (secondary track).

PHASE 02

STEP 03

Choose merge mode

bilingual (both languages visible per cue) or sequential (append second after first).

PHASE 03

STEP 04

For bilingual mode

choose cue order and delimiter. For sequential mode, choose gap behavior.

PHASE 04

STEP 05

Verify & Export

The merger processes both files, aligning or concatenating cues based on your selected mode.

PHASE 05

STEP 06

Delivery

Download the combined subtitle file with properly renumbered cues and valid timing structure.

PHASE 06

Engine Capabilities

Why Choose AllSubConverter?

Client-Side Privacy

Standard tools run in your browser so standard files are not uploaded to our servers.

Fast Local Parsing

Optimized processing engine parses and converts files directly in your browser.

Generous Batches

Up to 50 MB per file, 200 files or 1 GB total per batch.

Universal Compatibility

Runs in modern browsers across Windows, macOS, Linux, iOS, and Android.

Tool Suite

More Subtitle Tools

Subtitle Format Cleaner

Remove formatting, tags and noise

Subtitle Editor

Edit subtitle content and timings

Subtitle Sync & Timing Calibration

Adjust timing with millisecond precision

AI Subtitle Translator

Translate to 19 built-in target languages

Batch Subtitle Converter

Convert multiple files at once

Frequently Asked Questions

Bilingual mode aligns cues from both files by timestamp, displaying both languages simultaneously per cue. Sequential mode appends the second file's cues after the first file's cues, creating one continuous timeline. Use bilingual for dual-language display, sequential for combining multi-part videos.

Yes. Sequential mode is designed for this. Load Part 1 subtitles as the primary file and Part 2 subtitles as the secondary file. The merger offsets Part 2 timestamps to continue after Part 1 ends, producing a single combined subtitle file.

Both files can be in SRT, VTT, ASS, SSA, LRC, or SBV format. You can mix formats (e.g., SRT primary with VTT secondary). The output format is independent of the input formats.

When appending the second file, sequential mode calculates the timecode offset based on the last cue in the first file. It adds the duration of the first file to all timestamps in the second file, so cues appear in the correct chronological order in the combined output.

You can choose no gap (cues flow continuously), blank line (a visual separator between the two files' cues), or custom separator (a text marker like --- between sections). This helps identify where the second file's content begins.

Yes, completely free with no sign-up, no watermarks, and files up to 50 MB each. All processing happens in your browser.

Ready to convert your subtitles?