SRT Sync – Resync Subtitles Online
Fix subtitles that start in sync and slowly drift away from the dialogue. Set two sync points, convert the frame rate or apply a speed factor, then download the corrected file.
- Sync points
- Frame rates
- Private
- Free
Drop a subtitle file here
or
SRT · VTT · ASS / SSA · SBV · SUB · TTML · LRC · TXT
Your subtitles are processed on your device and are never uploaded.
Sync points
Pick a subtitle near the beginning and one near the end, then enter the time at which each line is really spoken. One point shifts everything; two or more also correct drift.
No subtitles match the current search or filter.
Next: SRT Time Shift SRT Validator
How to sync subtitles with a video
Three steps, no installation and no upload.
- 1
Open the subtitle file
Drop an SRT, VTT or ASS file, paste the text or try the sample file. You can also load the video from your device to check the timing; it is never uploaded.
- 2
Choose a sync method
Set sync points for a line near the beginning and one near the end, pick the source and target frame rate, or enter a factor. The preview shows the old and new times.
- 3
Download the synced file
Check the result in the preview or against the video, then download the corrected subtitle file or copy it to the clipboard.
Three ways to bring subtitles back in sync
From a single offset to a full frame-rate conversion.
Sync points
Enter when a line is really spoken: one point corrects an offset, two points also correct drift.
Up to 8 points
Add more points for piece-wise correction when parts of a file are off by different amounts.
Frame rate conversion
Convert between 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 fps, e.g. 25 fps subtitles for 23.976 fps video.
Factor
Multiply all times by a factor you already know, such as 1.0427 or 0.9590.
Video check
Load a local video, play it and take the real time of a line with one click.
Clear figures
See the offset, the speed factor and the drift per hour that result from your sync points.
Live preview
Every changed time is highlighted with the old value struck through before you download.
Private by design
The subtitle file and the video stay on your device; everything runs in your browser.
Why do subtitles drift out of sync, and how do you fix it?
There are two kinds of timing problems. A constant offset means the subtitles are early or late by the same amount from the first line to the last; this happens when a release has a longer intro or a different cut at the start. Drift means the error grows: the first lines fit, but after an hour the text is minutes away from the speech. Drift cannot be fixed with a simple shift, because every subtitle needs a different correction.
The most common cause of drift is a frame-rate mismatch. A film shot at 23.976 or 24 fps runs about 4 % faster when it is played at 25 fps, as on European PAL television and DVDs. Subtitles timed for the 25 fps version are therefore about 2.5 minutes early after one hour of a 23.976 fps video. Choosing 25 → 23.976 in the frame-rate method multiplies every time by 1.0427 and brings the whole file back in line.
When you do not know the frame rates, use sync points. Find a line near the beginning and one near the end, listen for the moment each is spoken, and enter those times. SRT Sync calculates the offset and the linear speed factor between them and applies both to every subtitle. If a file was cut differently in several places, for example around removed ad breaks, add up to eight points and each section is corrected separately.
Which sync method fits which problem?
| Symptom | Likely cause | Method |
|---|---|---|
| Same delay from start to end | Different intro or cut at the beginning | One sync point (constant offset) |
| Fine at the start, about 2.5 minutes early after an hour | 25 fps subtitles on 23.976 fps video | Frame rate 25 → 23.976 |
| Fine at the start, increasingly late | 23.976 fps subtitles on 25 fps video | Frame rate 23.976 → 25 |
| Growing error, frame rates unknown | Different speed or version of the video | Two sync points (offset + drift) |
| Timing jumps at certain scenes | Removed or added scenes, ad breaks | Three to eight sync points |
| You already know the speed ratio | Value from a calculator or another tool | Factor |
Tips
- If the delay is the same everywhere, Subtitle Delay or SRT Time Shift is quicker than setting sync points.
- Pick sync points that are far apart, a line in the first minutes and one near the end, and choose short lines with a clear start. Small listening errors then matter much less.
- Not sure whether it is a frame-rate problem? The Subtitle Timing Calculator compares subtitle time and real time at two points and tells you whether it looks like a frame-rate mismatch.
- After syncing, run the file through the SRT Validator to catch overlaps, and fine-tune single lines in the SRT Editor.
Frequently asked questions
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What is the difference between an offset and drift?
With an offset the subtitles are wrong by the same amount everywhere; with drift the error grows during the video. An offset needs one sync point or a simple shift, drift needs two sync points, a frame-rate conversion or a factor.
How many sync points do I need?
One point is enough for a constant offset and two points correct offset and linear drift. More points, up to eight, are only needed when sections of the file are off by different amounts.
How do I fix subtitles made for a 25 fps PAL version?
Choose the frame-rate method and convert from 25 to 23.976 fps (or to 24 fps, depending on your video). All times are stretched by about 4 %, which removes the drift of roughly 2.5 minutes per hour.
Do I have to load the video?
No. You can type in times that you read off in your media player. Loading the video only makes it easier, because the current position can be taken with one click; the video is played locally and never uploaded.
Why not just use the subtitle delay in VLC?
The subtitle delay in VLC (keys G and H on Windows and Linux) is temporary and only moves all subtitles by the same amount. It cannot correct drift, and the file itself stays wrong.
Can I sync several files at once?
No, SRT Sync works on one file at a time, because every file needs its own sync points. To move many files by the same amount, use SRT Time Shift, which handles up to 100 files.
More free subtitle tools
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