How to shift subtitle timing in 3 steps
- 1
Open your .ass or .ssa file
Drop it anywhere on the page or choose it with the button. The file stays on your device.
- 2
Enter the offset
Type a number of seconds, for example +1.5 to delay the subtitles or −0.8 to make them appear sooner. Check the “Now” column to see the new times.
- 3
Download the synced file
Click Download. The new file keeps your file name with the offset added, so you can tell it apart from the original.
What happens to styles and effects
The tool only rewrites the Start and End fields of each Dialogue and Comment line in the [Events] section. Your [Script Info], [V4+ Styles], fonts, positioning and override tags such as {\pos} and {\k} are left exactly as they were.
ASS times are stored to the hundredth of a second, so offsets are rounded to 0.01 s. Need a plain-text version for a TV or phone? Choose SRT under “Save as” and the styling tags are removed for you.
Subtitles too early, too late, or drifting?
Subtitles appear before the speech
The subtitles are ahead of the audio. Delay them with a positive offset: +2 moves every line 2 seconds later.
Subtitles appear after the speech
The subtitles are behind the audio. Speed them up to match with a negative offset: −1.5 brings every line 1.5 seconds earlier.
In sync at the start, wrong by the end
The gap grows because the subtitles were timed for a different frame rate. Set “Subtitles timed for” and “Your video plays at”, then fine-tune with an offset.
Frequently asked questions
Subtitles appear too early. Do I add or subtract time?
Add time. A positive offset such as +2 makes every subtitle appear 2 seconds later. If the subtitles appear too late, subtract time with a negative offset such as −2.
How do I calculate the time offset?
Play the video and pause on a line of dialogue. Note the time the person starts speaking and the time the subtitle appears. The difference is your offset. If the subtitle appears 1.5 seconds before the voice, enter +1.5. If it appears 0.8 seconds after, enter −0.8.
Easier still: open “Match a line, frame rate and format”, type the cue number and when that line is actually spoken, and the offset is worked out for you.
Why are my subtitles out of sync?
Usually the subtitle file was made for a different release of the video. A version with a studio logo, a recap or an extra few seconds at the start shifts every line by the same amount; that is fixed with an offset.
If the gap grows as the film goes on, the subtitles were timed for a different frame rate, for example 25 fps (UK and European TV) against 23.976 fps (film and most web releases). Pick both frame rates in the tool and it rescales every timestamp.
Which subtitle formats does it support?
SRT (SubRip), WebVTT (.vtt), ASS and SSA (Advanced SubStation Alpha) and SBV (YouTube captions). It can also convert any of them to SRT or WebVTT while it shifts them.
Are my files uploaded to your server?
No. Your subtitle file is read and rewritten by your own browser. Nothing is uploaded, nothing is stored, and the tool keeps working if you go offline after the page has loaded.