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Subtitle Editor

Fix subtitles that appear too early, too late or drift away from the video, and convert them between SRT, VTT and ASS.

Maintained by BrowserTools · Last updated 2026-09-29

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Subtitles that are out of sync are one of the most common annoyances when watching a film or series: the line appears a second before anyone speaks, or it starts in the right place and slowly falls behind until the end of the episode is unwatchable. This editor fixes both problems. Open or paste a SubRip (.srt), WebVTT (.vtt), Advanced SubStation (.ass or .ssa) or MicroDVD (.sub) file and every cue appears in a table with its start time, end time and text. Shift everything by a fixed amount with millisecond precision, or only the cues from a chosen line onwards, which is what you need when a TV recording has an ad break the subtitle file does not know about. The table updates as you type, showing the new times next to the old ones, so you can check the result before you save anything.

Frequently asked questions

How do I know whether to shift or to use two-point sync?
Compare an early line and a late line with the video. If both are off by the same amount (for example, both appear two seconds too early), a simple shift is enough. If the first line is nearly right but the gap grows as the video goes on, the subtitle was made for a copy with a different speed or frame rate, and two-point sync or a frame rate conversion is the fix.
Which way do I shift, positive or negative?
A positive value makes the subtitles appear later, a negative value makes them appear earlier. If the text shows up before the actors speak, the subtitles are early and you need a positive shift. You can type seconds (2.5 or -1.2), milliseconds (-1500ms) or a full timestamp such as -00:00:01,200.
How does two-point sync work?
You give the correct start time of two cues, normally the first and the last line of dialogue. The tool draws a straight line through those two points and moves every other cue onto it: each time t becomes the new first time plus (t minus the old first time) multiplied by a speed factor. Because the speed factor can be different from 1, it corrects a fixed delay and a gradual drift at the same time.
When should I convert from 23.976 to 25 fps?
When the subtitle was timed for the cinema or Blu-ray version of a film (23.976 frames per second) and you are playing a version made for PAL television or a European DVD (25 frames per second). The 25 fps copy runs about 4.1 percent faster, so the subtitles fall further behind as the film goes on. Choose "Timed for 23.976" and "Video is 25", or the opposite for the reverse case. A change between 23.976 and 29.97 usually does not affect timing, because that conversion repeats frames instead of speeding the film up.
Can I use a MicroDVD .sub file?
Yes. MicroDVD files store frame numbers instead of times, so the tool needs the frame rate. It reads it from the {1}{1} header line when the file has one and assumes 23.976 otherwise; you can pick another rate if the timing comes out wrong. Image-based VobSub .sub/.idx files from DVDs contain pictures of the text and cannot be edited as text.
Why do accented letters look wrong after I open a file?
Older subtitle files are often saved in a regional encoding instead of UTF-8. The tool tries UTF-8 first, falls back to Windows-1252 (Western European) and shows which one it used. If you see wrong characters, choose the right encoding from the list, for example Windows-1251 for Cyrillic, Windows-1250 for Central European languages or GBK for Simplified Chinese. The file you download is always UTF-8.
What does removing hearing-impaired text do?
Subtitles for the deaf and hard of hearing describe sounds and name speakers, for example [thunder], (whispering) or JOHN: Hello. The option removes text in square brackets, in parentheses and, if you tick it, speaker names in capitals followed by a colon. Cues that become empty are left out, and the table shows what each cue will contain after the cleanup.
What is kept when I convert between SRT, VTT and ASS?
Times and text always carry over, along with italic, bold and underline. SRT and ASS also keep {\an8} style placement tags. An ASS file shifted and saved again as ASS keeps its original styles and every override tag on lines whose text you did not change. ASS positioning, fonts and karaoke effects cannot be expressed in SRT or VTT, and VTT cue settings are only written back to VTT.
Is my subtitle file uploaded anywhere?
No. The file is read, edited and saved entirely in your browser. Nothing is sent to a server, so it keeps working even if your connection drops after the page has loaded.

About Subtitle Editor

When the delay grows over the course of the video, a fixed shift is not enough, because the subtitle was timed for a copy that runs at a different speed. The most frequent case is a film released at 23.976 frames per second in cinemas and on Blu-ray, and at 25 frames per second in countries that used PAL television: the PAL copy plays about 4 percent faster, so a two hour film ends almost five minutes sooner. Two-point sync solves this without any maths on your side. Find the first and the last spoken line in your video, type the times they really appear, and every cue in between is stretched or squeezed in a straight line to fit. The tool tells you the speed factor it used and, if it matches a known frame rate change, which one. If you already know the two frame rates, the conversion presets (23.976, 24, 25, 29.97 and more) do the same thing in one click.

The editor also cleans up the text. It can remove hearing-impaired descriptions such as [door slams] or (laughing) and speaker labels written in capitals, strip italic, colour and position tags, fix cues that overlap the next one, give very short cues a minimum on-screen time and renumber everything from 1. You can correct the text of any cue directly in the table. Files in older encodings are detected automatically: the tool tries UTF-8 first and falls back to Windows-1252, tells you which one it used, and lets you pick another (Cyrillic, Greek, Arabic, Chinese, Japanese and more) if the letters look wrong. The result is saved as UTF-8 in SRT, WebVTT or ASS with a correct header and timestamp format, and nothing is uploaded: the whole file is processed in your browser.

Why PAL films finish early

Cinema film runs at 24 frames per second, and European PAL television ran at 25. Instead of converting frames, broadcasters and DVD makers simply played the film 4 percent faster, one film frame per TV frame. A 120 minute film lasted about 115 minutes on PAL television, and voices and music rose by about two thirds of a semitone unless the audio was corrected.

North American NTSC television had the opposite problem. Its colour system runs at 29.97 frames per second, a hair slower than 30, a compromise made in 1953 so the new colour signal would not interfere with the sound carrier. Film was fitted to it by repeating fields in a 2:3 pattern, which keeps the running time, but the film itself had to be slowed by 0.1 percent, from 24 to 23.976 frames per second. That tiny difference is why subtitles made for a 24 fps file drift by about seven seconds over a two hour film when played against a 23.976 copy.

Those two decisions, one about television sound in the 1950s and one about avoiding expensive conversions, are the reason subtitle tools still ship with frame rate presets today.

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