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Echoryte

Free · No sign-up · Nothing uploaded

Subtitle Sync: Shift SRT Timing Online

Subtitles a second early or late? Use this free subtitle sync tool to shift every SRT cue by a set delay, then download the corrected file. No upload needed.

Open the tool
You get
SRT file with corrected timing
Runs
In your browser, on your device
Costs
Nothing, with no account

Private by design

Sync your subtitles

Your file stays on this device.

No upload. No sign-up.

Step by step

How to use it

  1. Measure the gap

    Play the video and note roughly how far off a line is. Half a second is 500; two seconds is 2000. An estimate is fine — you can adjust and re-run.

  2. Enter the offset

    Positive numbers push subtitles later, negative numbers pull them earlier. Choose your .srt file and apply the change.

  3. Check three points

    Download and test near the start, the middle, and the end. If all three now match, a single shift was the right fix.

  4. Fine-tune if needed

    Still slightly off? Run the corrected file through again with a smaller offset. Two quick passes beat guessing the exact number first time.

What actually changes

Before · out of sync
12
00:04:31,000 --> 00:04:33,500
Did you hear that?
After · shifted -1500 ms
12
00:04:29,500 --> 00:04:32,000
Did you hear that?

A shift of -1500 pulls every cue 1.5 seconds earlier. Cue text, numbering, and each cue’s duration stay exactly as they were.

Features

Why use this one

  • Millisecond precision

    Offsets are entered in milliseconds, so you can nudge a file by 250 ms rather than rounding to the nearest second. Duration of each cue is preserved, only its position moves.

  • Every cue moves together

    One number is applied to all cues at once. A three-hour subtitle file with 2,000 lines takes the same single click as a two-minute clip.

  • Guards against negative times

    If a backwards shift would push a cue before 00:00:00, the tool refuses and tells you rather than silently clamping cues to zero and stacking them on top of each other.

  • Local, private, reversible

    The shift runs in your browser and writes a new file. Your original .srt is never modified, so an over-corrected guess costs you nothing but another attempt.

  • No video upload

    Unlike automatic sync services, this tool never needs your video. Nothing multi-gigabyte has to travel over your connection just to move some text.

  • Iterate until it fits

    Run the tool again on the corrected file with a smaller offset to fine-tune. Two or three quick passes usually beats trying to nail the number first time.

The translation is fine, the spelling is fine, and yet every line lands two seconds after the actor speaks. That is a constant offset, and it is the easiest subtitle problem to fix. This subtitle sync tool moves all the cues in an SRT file by an amount you choose — forwards or backwards, down to the millisecond — and gives you a corrected file to download. No video upload, no waveform analysis, no account.

Which direction should the shift go?

Watch one clear line of dialogue and decide which came first. If the text appears before you hear the words, the subtitles are early and need pushing later: use a positive number, such as 1500 for a second and a half. If you hear the words before the text arrives, the subtitles are late and need pulling earlier: use a negative number, such as -1500. Guessing the wrong sign is harmless — the original file is untouched, so you just run it again the other way.

When a single shift is not enough

A constant offset is one problem; drift is another. If subtitles line up in the opening scene but are five seconds out by the end, the file was almost certainly timed against a different frame rate — a 25 fps to 23.976 fps mismatch is the classic cause — and no single offset can fix it. Likewise, if your copy of the video includes an intro, an advert break, or a scene that the subtitler did not have, the offset changes partway through. In both cases you either need a subtitle file made for your exact release, or you split the file and shift each part separately in the subtitle editor.

How to measure the offset accurately

Subtitle sync is only as good as the number you feed it, and guessing works, but two minutes of measuring saves several rounds of trial and error. Find a moment where a single short line of dialogue starts cleanly after a pause — the first line after an establishing shot is ideal. Step through with your player’s frame-by-frame keys and note the timecode where you first hear the word. Then open the subtitle file and read the start time of that same cue. The difference between the two numbers, in milliseconds, is your offset, and its sign tells you the direction: if the cue starts earlier than the audio, the subtitles are early and the shift is positive. Check the result at a second point far from the first before you call it done.

FAQ

Common questions

How do I know how many milliseconds to shift?

Pause on a line of dialogue and compare when the subtitle appears against when you hear the words. One second is 1000 milliseconds, so most corrections land between 500 and 5000. Start with your best guess, check the result, and refine — a second pass with a smaller number is quicker than measuring precisely up front.

Does this subtitle sync tool listen to my audio?

No. This is a manual shift, not automatic alignment. You supply the offset and the tool applies it. That is deliberate: it needs no video upload, works offline once loaded, and gives a predictable, reversible result instead of an algorithmic guess.

My subtitles drift further out as the video plays. Can I fix that?

Not with a single shift, because the error is proportional rather than constant. That pattern points to a frame-rate mismatch between the subtitle file and your video. Look for a subtitle release that names your exact video version, or split the file and shift sections independently.

Why was my negative shift rejected?

Because it would have moved at least one cue to a time before the video starts. Subtitle timings cannot be negative. Reduce the size of the shift, or open the file in the subtitle editor and adjust the first few cues by hand before shifting the rest.

Can I shift a VTT file too?

This tool takes SRT. If you have WebVTT, convert it to SRT first, apply the sync, and convert back to VTT. Both conversions preserve timing exactly, so nothing is lost in the round trip.

Will the cue numbers or durations change?

Neither. Cue numbering stays in order and each cue keeps the same on-screen duration. Only the start and end times move, by exactly the amount you entered.

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