Detect and correct overlapping subtitle timestamps. Works with .srt and .vtt files. Overlapping cues are pushed forward to where the previous cue ended; non-overlapping cues pass through unchanged.
Fix Overlapping Subtitles Online Free
Detect and fix overlapping subtitle cues in .srt and .vtt files — free and instant.
What Overlapping Subtitles Are and Why They Need Fixing
Overlapping subtitles happen when one cue's start time falls before the previous cue's end time, so two lines briefly stack on screen at the same moment. This causes flickering text, rapid on-screen changes, and occasional upload warnings on platforms that prefer strictly sequential cues.
The Subtitle Overlap Fixer scans your SRT or VTT/WebVTT file for these conflicts and pushes overlapping cues forward to where the previous cue ended. Cue text, cue numbers, and inline formatting tags are left untouched. Everything runs in your browser — no uploads, no sign-up, no install.
How the Subtitle Overlap Fixer Works
The tool walks through your file line by line and looks at every timestamp line (HH:MM:SS,mmm --> HH:MM:SS,mmm for SRT, HH:MM:SS.mmm --> HH:MM:SS.mmm for VTT). For each cue, it compares the start time to the end time of the previous cue. If the start is earlier than the previous end, the cue is overlapping, and its start time is pushed forward to where the previous cue ends. If pushing the start forward would leave the cue shorter than 300 milliseconds, the end time is extended so the cue stays on screen long enough to read.
1. Choose your SRT or VTT file (or paste the contents)
Click Choose File to load a subtitle file from your device, or paste the contents directly into the input box.
2. Click "Fix Overlaps"
The tool processes the file in a single pass and writes the corrected version to the output box. Cues that were already in order are left at their original timings.
3. Download the fixed file
Click Download to save the corrected file. The output keeps the same format as the input — .srt in, .srt out; .vtt in, .vtt out.
Before and After
Input (SRT with cue 2 overlapping cue 1):
1 00:00:01,000 --> 00:00:03,500 First line of dialogue. 2 00:00:03,000 --> 00:00:05,000 Second line starts before the first ends. 3 00:00:05,200 --> 00:00:07,000 Third line — no overlap.
Output (cue 2's start pushed to cue 1's end):
1 00:00:01,000 --> 00:00:03,500 First line of dialogue. 2 00:00:03,500 --> 00:00:05,000 Second line starts before the first ends. 3 00:00:05,200 --> 00:00:07,000 Third line — no overlap.
Cue 2's start time was pushed from 00:00:03,000 to 00:00:03,500(matching cue 1's end). Cue 3 was untouched because its original start time was already past cue 2's new end. Dialogue, cue numbers, and blank-line spacing pass through unchanged.
VTT Cue Settings and What Gets Dropped
VTT files can include cue settings on the timing line itself, for example: 00:00:01.000 --> 00:00:02.000 line:50% align:center. When the tool rewrites a timing line, it keeps only the start and end timestamps — the cue settings on that line are dropped. This happens on every cue, not just overlapping ones, because every timing line gets rewritten.
Other VTT structures pass through unchanged: WEBVTT headers, NOTE blocks, STYLE blocks, REGION blocks, and named cue identifiers. Italic, bold, font, and underline tags inside dialogue text (<i>, <b>, <font>, <u>) are preserved on every cue because they live on text lines, not timestamp lines.
When to Use the Subtitle Overlap Fixer
Overlap fixing is most useful in these workflows:
- After running AI auto-captioning (Whisper, YouTube auto-captions, Otter.ai) — these tools often produce back-to-back cues with millisecond overlaps that flicker on playback.
- After merging multiple subtitle files — if two source files share the same time range, their cues can interleave and overlap.
- Before exporting from a subtitle editor for professional captioning deliveries, where clean timing is expected.
- Before uploading to platforms — most modern players tolerate small overlaps, but cleaner timing reduces flicker in players that don't.
- After a partial time-shift — if you shifted only part of a file, the boundary cues may now overlap.
Who Uses This Tool
Video editors and captioners cleaning up AI-generated subtitle drafts. Translators who merge source-language and target-language files. YouTubers preparing captions for upload. Documentary and film teams polishing deliverables. Anyone who downloaded SRT or VTT files from auto-captioning services and noticed flicker on playback.
Why Use This Subtitle Overlap Fixer
- Honest, deterministic logic — the tool only changes timestamps on cues that overlap. Everything else passes through.
- No uploads — your file is read into the browser tab and processed locally. Nothing is sent to a server.
- Both SRT and VTT supported — the tool detects the format and outputs the matching decimal separator.
- Free, no account, no install — open the page, fix the file, close the tab.
- Single-pass line-by-line processing — fast even on feature-length captions with thousands of cues.
Related Subtitle Tools
Other free subtitle tools you can use alongside the Overlap Fixer:
Frequently Asked Questions (FAQ)
What does "overlapping subtitles" mean?−+
Overlapping subtitles happen when one cue's start time is earlier than the previous cue's end time, so two subtitle lines briefly appear on screen at the same moment. This causes flickering, doubled text, or upload warnings on platforms like YouTube. The fix is to shift the later cue so it begins after the earlier one ends.
How does this tool fix overlapping subtitles?−+
For each cue, the tool compares its start time against the previous cue's end time. If the cue would overlap, its start time is pushed forward to where the previous cue ended. Cue text, cue numbers, and inline formatting tags are left untouched — only the timestamps on conflicting lines are rewritten.
Does the tool change my dialogue, cue numbers, or formatting tags?−+
No. The tool only rewrites timestamp lines. Cue numbers, dialogue text, line breaks, italic and bold tags, font tags, underline tags, speaker labels, and blank line spacing all pass through unchanged. The output file keeps the same structure as the input — just with corrected timings on overlapping cues.
Does it handle both SRT and VTT files?−+
Yes — SRT and VTT timing lines are both detected and corrected, and the output uses the input format's decimal separator (comma for SRT, dot for VTT). One caveat: VTT cue settings on timing lines, like line:50% or align:center, are dropped during processing. Every timing line is rewritten with just the timestamps.
What happens to cues that are too short after a fix?−+
The tool enforces a minimum cue duration of 300 milliseconds. If pushing a cue's start time forward would leave it shorter than 300 ms, the end time is extended so the cue stays on screen long enough to read. Cues already longer than 300 ms are left at their original duration.
Will fixing one overlap affect later cues?−+
Most of the time, no. A fix only touches cues whose start time falls before the previous (corrected) end time. However, if extending a very short cue to the 300 ms minimum makes it overlap the next cue, that next cue gets pushed too — so a chain of very short overlaps can cause a small cascade forward.
What causes overlapping subtitles in the first place?−+
Common sources include AI auto-captioning tools (Whisper, YouTube auto-captions), merging subtitle files from different parts, manual edits where end times were not tightened, frame-rate conversions, and copy-paste mistakes. Overlaps are especially common in files where multiple speakers talk over each other or where captions were generated in bursts.
Does this tool require an upload or install?−+
No. The Subtitle Overlap Fixer runs entirely in your browser using local JavaScript. Your subtitle file never leaves your device, no account is required, and there is nothing to install. The tool is free with no usage limits, no watermark on the corrected file, and no ads injected into the output.
Can it handle large subtitle files?−+
Yes. The tool processes files line by line in a single pass, so even subtitles for long films or full TV episodes with thousands of cues finish in well under a second on a typical laptop. Performance is bound only by your browser since nothing is sent to a server.
Will it fix subtitles exported from Whisper, YouTube auto-captions, or Premiere?−+
Yes. Subtitle files exported from Whisper, YouTube Studio auto-captions, Adobe Premiere, DaVinci Resolve, Final Cut Pro, Aegisub, and most other caption tools are plain SRT or VTT and work directly. The tool reads the file as text, finds overlapping timing lines, and rewrites them — the source tool does not matter.
What's the difference between this and a subtitle time shifter?−+
A time shifter moves every cue forward or backward by the same amount, used when subtitles are uniformly out of sync with video. This Overlap Fixer only changes timestamps on cues that actually conflict with each other. The two tools solve different problems and can be used together in any order.
Does it work as an SRT to VTT converter or vice versa?−+
No — the output keeps the same format as the input. If you upload SRT, you get SRT back. If you upload VTT, you get VTT back. To convert between formats, use the dedicated SRT to VTT Converter or VTT to SRT Converter, then run the Overlap Fixer if needed.