Subtitle sync online shift, stretch or fix the frame rate.
To sync subtitles, find out how early or late they are and apply that difference to every line. This tool does it with your SRT or VTT: it shifts everything by milliseconds, converts between frame rates, and fixes subtitles that slowly drift out of sync by using two reference points.
Free, no sign-upUse this when the subtitles start in sync and slowly drift away from the audio.
How to sync your subtitles
- 01
Paste or drop the SRT or VTT
SRT, VTT and ASS all work. You get it back in the same format (ASS comes back as SRT).
- 02
Pick the kind of fix
Shift everything by a few seconds, convert the frame rate, or use two points when the subtitles drift further off over time.
- 03
Download and check in a player
Play the video with the new file and spot-check the start, the middle and the end before you publish or deliver.
How to shift an SRT by a few seconds
Play the video and note the exact moment the first line is spoken. Compare it with the time the SRT gives that same line. The difference is your offset. If the line starts at 00:00:12,400 and the subtitle shows up at 00:00:10,000, the subtitles are 2.4 seconds early: shift everything 2400 ms later.
If the problem only starts partway through, for example after a break that was cut from the recording, use "starting at subtitle #". Everything before that line stays put and only the rest moves.
Shift too far back and some subtitles would land before zero. A subtitle that still ends after zero now starts at 0, and one that would end before zero is removed. The tool tells you how many.
Why do subtitles drift out of sync over time?
When subtitles start in sync and slowly slide away from the audio, it is not a fixed delay. They were timed for a version of the video that plays at a different speed. The classic case is 25 fps versus 23.976 fps: the same program runs about 4% shorter at 25 fps.
In practice, subtitles timed for 25 fps and played over a 23.976 fps video show up earlier and earlier: the gap grows by about 2.6 seconds every minute. After an hour the gap is over two and a half minutes. Between 23.976 and 24 fps, or 29.97 and 30 fps, it is much smaller: 0.1%, or 3.6 seconds per hour.
Other common causes are a different cut of the video, bumpers or ad breaks that exist in one version and not the other, and livestream recordings that started rolling before the show. For those, the two-point fix works best.
| Subtitles made for | Video at | Gap after 60 min |
|---|---|---|
| 25 fps | 23.976 fps | about 2 min 34 s |
| 23.976 fps | 24 fps | about 3.6 s |
| 29.97 fps | 30 fps | about 3.6 s |
| 25 fps | 25 fps | none |
How to convert subtitle timing between frame rates
In "change frame rate" mode, choose the frame rate the subtitles were made for and the one your video actually uses. We multiply every timestamp by the ratio between the two. Subtitles moved from 25 fps to 23.976 fps get every time multiplied by about 1.0427.
Not sure about the original frame rate? Go by the symptoms: if the subtitles run out minutes before the video ends, they came from a faster version. If they run past the end, they came from a slower one.
- Supported rates: 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 fps.
- The file stays SRT or VTT, with the same numbering and the same text.
- No line is cut: only the timing changes.
Two-point sync: fix offset and drift in one go
When you don't know the cause, use two points. Pick one subtitle near the start and one near the end, find the correct time for each in the video, and type them in. We work out the correction that puts both points in place and apply the same rule to every subtitle in between.
Example: subtitle #1 shows at 00:00:10,000 but the line is spoken at 00:00:12,400. Subtitle #850 shows at 01:28:15,000 but the line is at 01:32:10,000. With those two pairs the whole file lines up, no frame rate math needed.
More than a subtitle synchronizer. Subtitles that start out in sync.
See also
Frequently asked questions
How do I fix subtitles that are out of sync?
Play the video, note when the first line is actually spoken and compare it with the subtitle's time in the SRT. If the subtitle shows after the line, shift it earlier by the difference. If it shows before, shift it later. Paste the file above, enter the value and download the fixed SRT.
How do I shift an SRT by a few seconds?
In "shift earlier or later" mode, type the amount in milliseconds, seconds or as 00:00:01,500 and choose the direction. Every subtitle moves together. You can also start from a specific subtitle and leave the earlier ones as they are.
Why do subtitles drift over time?
Because they were timed for a version of the video at another frame rate or with a different cut. Between 25 and 23.976 fps the gap grows by about 2.6 seconds per minute. Use "change frame rate" or the two-point fix.
How do I convert timing between frame rates?
Pick the frame rate the subtitles were made for and your video's frame rate. We rescale every timestamp by the ratio between them. If you don't know the original rate, the two-point fix gets you to the same result without it.
Does it work with VTT files?
Yes. It takes SRT and WebVTT, and the file comes back in the same format, as UTF-8. To switch formats, run it through the SRT, VTT and TXT converter after syncing.
Generate captions for your video automatically. In sync from the start.
Upload a video or paste a YouTube link. We transcribe it word by word, each word timed, and you download the SRT, captioned clips and, on Studio and Agency, your editor's timeline.
See the result on your own recording before adding a card.