Out-of-sync subtitles are one of the most frustrating things to sit through. The character speaks and the subtitle appears two seconds later — or worse, before they've said a word. The good news is that most sync problems have a simple cause and a simple fix. This guide walks you through exactly how to resync subtitles with video, for free, in your browser.

Why are subtitles out of sync?

Before fixing the problem it helps to understand why it happens. There are two main causes:

Constant offset. The subtitles are consistently early or late by the same amount throughout the entire video. This is the easiest fix — you just shift all timestamps by that amount. It usually happens when subtitles were made for a different version of the video (different intro length, different cut) or when downloading subtitles from a third-party site.

Drift. The subtitles start roughly in sync but gradually get further off as the video progresses. This is trickier — it means the subtitle file's frame rate doesn't match the video's frame rate. A subtitle file made for a 25fps video will drift noticeably when played with a 23.976fps video over a long runtime.

This guide focuses on the constant offset fix, which covers the majority of cases.

How to resync subtitles online (step-by-step)

Our Subtitle Time Shifter adjusts all timestamps in your SRT or VTT file by a set amount — forwards or backwards.

Step 1: Play your video and note when a line of dialogue is spoken that you can see in the subtitle file. For example, find the first spoken line.

Step 2: Note the timestamp on screen when the dialogue is spoken. Then open your subtitle file (it's a plain text file — you can open it in Notepad) and find the timestamp for that same line.

Step 3: Calculate the difference. If the subtitle shows 00:00:05,000 but the dialogue actually happens at 00:00:08,000, your subtitles are 3 seconds early — you need to shift forward by +3000 milliseconds.

Step 4: Open the Subtitle Time Shifter and upload your subtitle file.

Step 5: Enter your offset in milliseconds. Use a positive number to shift subtitles later (if they appear too early) and a negative number to shift them earlier (if they appear too late).

Step 6: Download the adjusted file and test it in your player.

How to measure the sync offset accurately

The most reliable method is to find a moment in the video with a sharp, clear audio cue — a door slam, a gunshot, a clap — where you can also see the corresponding subtitle text.

1. Pause the video exactly when the sound occurs. Note the video timestamp (shown in your player's progress bar).
2. Open the SRT file in a text editor. Find the matching subtitle cue.
3. Note the start timestamp on that cue.
4. Subtract: video timestamp − subtitle timestamp = offset

If the result is positive, subtitles are early (appearing before the dialogue) — shift them forward. If the result is negative, subtitles are late — shift them backward.

Common sync scenarios

Subtitles are a few seconds early throughout. Enter a positive offset equal to the gap. For example, if subtitles are consistently 2.5 seconds early, enter +2500.

Subtitles are late throughout. Enter a negative offset. If subtitles are 1.8 seconds late, enter -1800.

The first subtitle is in sync but later ones drift. This is the frame rate mismatch problem. You'll need to use desktop software like Subtitle Edit or Aegisub which supports frame rate conversion. The online time shifter won't fix a drift — it applies the same offset to every cue.

Only part of the file is out of sync. If your video has a mid-point cut that knocked only the second half of the subtitles out of sync, you can use our Subtitle Splitter to divide the file at the problem point, fix the second half separately, then re-merge with the Subtitle Merger.

Adjusting subtitle timing without any tools

If you're comfortable editing text files, you can manually adjust subtitle timestamps. SRT timestamps follow this format:

00:01:23,456 --> 00:01:26,789

That's hours:minutes:seconds,milliseconds. To shift a cue forward by 2 seconds, add 2 to the seconds value in both the start and end timestamps. For a small file with a consistent offset, this is feasible. For anything more than a few lines, use the online tool — it's faster and error-free.

Subtitle sync for specific video players

VLC Media Player has a built-in sync shortcut. During playback, press G to delay subtitles (shift later) or H to advance them (shift earlier) — each press moves by 50ms. This adjusts sync for the current session only. To save the corrected timing permanently, edit the file itself using our Time Shifter.

Plex and Jellyfin also have subtitle offset controls in the player settings. Again, these are session-only adjustments unless you modify the file.

Smart TVs typically don't offer offset controls. Fixing the file itself using our online tool is the only reliable solution.

After syncing: other subtitle issues to fix

Once timing is correct, check for these common follow-on problems:

• Overlapping subtitles — two cues that cover the same time range. Use our Subtitle Overlap Fixer to resolve these automatically.
• Wrong format — if your player needs VTT but you have SRT, use our SRT to VTT Converter.

FAQ

How do I know if my subtitles are early or late? Play the video and watch a few lines. If the text appears before the character speaks, the subtitles are early. If the text appears after they've started speaking, they're late.

What unit does the time shifter use? Milliseconds. 1 second = 1000 milliseconds. So a 3-second shift is 3000ms, and a half-second shift is 500ms.

Can I sync VTT files as well as SRT? Yes. The Subtitle Time Shifter works with both .srt and .vtt files.

Will the sync fix work for the entire file? Yes, as long as your offset is constant throughout. The tool shifts every cue by the same amount. If the sync drifts (gets worse as the video progresses), you have a frame rate issue that requires different software.

I fixed the sync but now some subtitles overlap. What do I do? Run the adjusted file through our Subtitle Overlap Fixer. Shifting all cues forward or backward can sometimes cause cues that were close together to overlap.

Is there a limit to how far I can shift subtitles? No practical limit. You can shift by seconds, minutes, or even hours if needed.

Can I partially sync — fix only some cues? Not with the Time Shifter, which adjusts all cues uniformly. To fix only a section, split the file at the problem point using our Subtitle Splitter, adjust only that section, then re-merge.