Subtitle Time Shifter
Supports SRT & VTTDrop your .srt or .vtt file here
or click to browse
Use + to delay (push later) · − to advance (push earlier)
Quick Presets
3. Download Result
Upload a file and set an offset
Your synced subtitle file will appear here
How to Fix Subtitle Delay in 4 Steps
Upload your SRT or VTT file
Click the upload area or drag-and-drop your subtitle file. Both SubRip (.srt) and WebVTT (.vtt) formats are supported.
Determine your offset
Play your video and note when a subtitle appears vs. when the dialogue actually occurs. The difference is your offset — e.g. if the subtitle appears 2 seconds after dialogue, use −2s. If subtitles are 2 seconds early, use +2s.
Enter the shift amount or click a preset
Type your offset in the shift field (e.g. +2s, −1.5s, 500ms) or click one of the quick preset buttons. Use + to push subtitles later; use − to pull them earlier.
Download the synced file
Click Shift Subtitles. Every timestamp in the file is shifted by your chosen amount. Preview the first few lines, then download the corrected file. No text content is changed — only the timestamps.
Subtitle Delay vs. Subtitle Drift — What's the Difference?
Not all sync problems are the same. Before you apply a shift, it helps to know which type you have — because only constant offset is fixed by a time shifter.
| Type | What It Looks Like | Common Cause | Fix |
|---|---|---|---|
| Constant offset | Every subtitle is off by the same amount throughout the video | Subtitle file made for a different video version or release | ✅ Use this time shifter — one shift fixes the whole file |
| Subtitle drift | Subtitles start in sync but slowly drift out over time | Frame rate mismatch (e.g. 23.976fps subtitle on a 25fps video) | ⚠️ Needs a linear correction tool — a fixed offset won't help |
| Partial offset | Some parts are fine; certain scenes are off | Video was cut, trimmed, or chapters were inserted | ✅ Split the file at the cut point and shift each part separately |
Quick test for drift: Check the sync at the beginning AND end of the video. If the offset is the same at both points, you have a constant offset — use this tool. If the offset is different (e.g. 1 second off at minute 10, 3 seconds off at minute 90), you have drift — you need a frame-rate correction tool.
How to Measure Your Subtitle Offset
The most common question: “How do I know how many seconds my subtitles are off?” Here's a simple 3-step method:
- 1
Find a clear dialogue moment
Pick a moment where a character says something very short and distinct — ideally a single word you can identify precisely (e.g. a name, a shout, a one-word response).
- 2
Note the video timestamp and subtitle timestamp
Pause the video the instant the dialogue occurs. Note the video player's time display (e.g. 0:04:32). Now look at when the subtitle appears. If the subtitle shows at 0:04:30, it's 2 seconds early. If it shows at 0:04:35, it's 3 seconds late.
- 3
Calculate the shift
Subtitles 2 seconds early → enter +2s (push subtitles later). Subtitles 3 seconds late → enter −3s (pull subtitles earlier). In VLC you can also use the subtitle delay display (G/H keys) to find the exact offset, then apply it permanently here.
VLC Subtitle Delay vs. Permanently Fixed File
VLC Media Player lets you adjust subtitle delay temporarily using the H / G keys. But this fix only lasts for that playback session — it doesn't change the file. Next time you or someone else opens the file, the subtitles are out of sync again.
| Method | How it works | Permanent? | Works on other devices? |
|---|---|---|---|
| VLC H/G keys | Adjusts delay in the VLC player UI only | No — resets on next open | No — VLC-only, that session only |
| VLC player settings save | Save delay in VLC preferences for that file | Semi-permanent (VLC only) | No — other players or devices won't see it |
| This time shifter (fossatech) | Edits the actual timestamps inside the .srt/.vtt file | Yes — file is permanently fixed | Yes — any player, any device, any platform |
Understanding the SRT Timestamp Format
An SRT file is plain text. Each subtitle entry has three parts: a sequence number, a timestamp line, and the subtitle text. Only the timestamp line is modified by this tool — your text and formatting are never changed.
Example SRT entry:
1 00:00:01,500 --> 00:00:03,750 Hello! Welcome to the movie. 2 00:00:05,000 --> 00:00:07,200 This is the second subtitle.
Format: HH:MM:SS,mmm → hours : minutes : seconds , milliseconds
VTT format uses HH:MM:SS.mmm (period instead of comma)
After shifting by +2s, the first entry's timestamps become 00:00:03,500 → 00:00:05,750. The sequence number and subtitle text stay exactly the same.
Frequently Asked Questions
What is a subtitle time shifter?
A subtitle time shifter is a tool that adds or subtracts a fixed time offset from every timestamp in a subtitle file. If your subtitles appear 2 seconds too early, shifting by +2s pushes all subtitles 2 seconds later. If they appear 3 seconds too late, shifting by −3s pulls them 3 seconds earlier. Only the timestamps change — the subtitle text is never modified.
What's the difference between positive (+) and negative (−) shift values?
A positive value (e.g. +2s) delays subtitles — they appear later. Use this when subtitles appear before the dialogue. A negative value (e.g. −2s) advances subtitles — they appear earlier. Use this when subtitles appear after the dialogue.
How do I know how many seconds my subtitles are off?
Play your video and pause it the instant you hear a specific word. Note the video timestamp. Then find that subtitle in the file and note its start time. The difference is your offset. In VLC, press H or G while playing to adjust the subtitle delay display — the value shown is your exact offset. Then apply that same value here to permanently fix the file.
Why are my subtitles out of sync?
The most common reasons are: (1) The subtitle file was made for a different version of the video (e.g. a different release cut or encoding). (2) The video was trimmed or edited after the subtitles were created. (3) There's a frame-rate mismatch between the subtitle source and the video (this causes drift, not a constant offset).
What is subtitle drift and can this tool fix it?
Subtitle drift means the subtitle offset changes throughout the video — subtitles might be 1 second off at the start but 5 seconds off by the end. This is caused by a frame-rate mismatch (e.g. 23.976fps vs 25fps). A fixed-offset time shifter cannot fix drift — you need a linear correction (also called speed adjustment or FPS correction) tool for that.
Can I sync both SRT and VTT subtitle files?
Yes. This tool supports both SubRip (.srt) and WebVTT (.vtt) formats. SRT uses comma-separated milliseconds (HH:MM:SS,mmm) while VTT uses period-separated milliseconds (HH:MM:SS.mmm) — the tool handles both automatically based on the file extension you upload.
What if shifting results in negative timestamps?
If shifting backward would result in a subtitle starting before 00:00:00,000 (i.e. a negative timestamp), the tool clamps it to 00:00:00,000. The subtitle won't disappear — it will appear at the very start of the video instead. This only affects subtitles very close to the beginning of the file.
Does this tool work for Netflix, YouTube, or streaming subtitle files?
Yes, if you have downloaded the subtitle file from those platforms in SRT or VTT format, this tool can fix the timing. Netflix subtitles are typically delivered as .srt or .vtt files. YouTube subtitle exports are in .srt format. Upload the file, apply the offset, and the fixed file is ready to re-import.
Can I shift subtitles by milliseconds for precise sync?
Yes. You can enter any value in milliseconds: e.g. 750ms or −250ms. The tool supports ms, s, m, and h units. Fractional seconds are also supported: 1.5s = 1500ms.
Does the shift change my subtitle text or formatting?
No. Only the timestamp lines (the HH:MM:SS,mmm --> HH:MM:SS,mmm lines) are modified. All text content, HTML tags, line breaks, and subtitle sequence numbers remain completely unchanged.
Is this tool safe? Does it send my subtitle file to a server?
Your subtitle file never leaves your browser. The entire conversion runs as JavaScript in your browser tab. No data is uploaded to any server. The file is processed locally and downloaded directly from your browser.
Can I fix subtitles that only go out of sync in certain scenes?
If specific scenes have a different offset, you can fix them by editing the SRT file in a text editor — split the file at the problem point, shift each section by a different amount, and merge them back. Our tool applies a single constant offset to the entire file.
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