SubtitleMedic

Convert SUB to SRT

Turn frame-based MicroDVD .sub subtitles into SubRip with real times that every player reads.

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How to convert SUB to SRT

  1. Open your .sub file

    Drop one MicroDVD file into the box above, or click to browse. It’s read by your browser and never uploaded.

  2. Check the frame rate

    The frame rate is shown next to the file name. If the file doesn’t state one, the tool starts from 23.976 and says it is a guess; pick the rate of your video and the times follow.

  3. Download the .srt file

    Save the converted file. It keeps the original name with the new extension, so movie.sub becomes movie.srt.

What a MicroDVD file looks like

A MicroDVD file has one subtitle per line: the frame it appears on, the frame it disappears on, then the text.

{1}{1}23.976
{75}{131}Is this seat taken?
{144}{213}Only by my coat.|Sit, please.

Frames, not times. {75}{131} means “from frame 75 to frame 131”. When that is depends on the video: at 25 frames per second frame 75 is exactly 3 seconds in, at 23.976 it is a little later.

The frame rate line. Many files open with a line like {1}{1}23.976. It is not a subtitle: it tells the player which frame rate the file was made for. Files without it leave the player guessing.

Line breaks. A vertical bar | starts a new line inside one subtitle.

Style codes. {y:i} makes a line italic, {y:b} bold, and other codes set a colour, a font or a position.

How SubRip writes the same subtitles

1
00:00:03,128 --> 00:00:05,464
Is this seat taken?

2
00:00:06,006 --> 00:00:08,884
Only by my coat.
Sit, please.

Numbers. Each block starts with its number, counting from 1.

Real times. Start and end are written as hours, minutes, seconds and milliseconds. The file no longer depends on a frame rate, so every player shows each line at the same moment.

Text. The bar becomes a real line break, and italic, bold and underline become the tags SubRip uses. The frame rate line is left out, because SubRip has no use for it.

Why the frame rate matters

Converting frames to times is a division: frame number divided by frames per second. Use 25 for a file made at 23.976 and every time comes out about 4% too early, which is two and a half seconds after the first minute and more than four minutes by the end of a film.

That is why this page shows the frame rate before anything else. If the file states its rate, that rate is used. If not, the tool starts from 23.976, the most common rate for films, and marks it as a guess.

The subtitles fit at the start and drift later: the rate is wrong. Change it next to the file name.

The subtitles are off by the same amount from start to end: the rate is right and the file simply starts too early or too late. Convert it, then move every line with Shift Subtitle Timing.

The file is right for one release and you have another: a film at 23.976 and its PAL release at 25 need different times. Convert here with the rate the file was made for, then stretch the .srt with Change Subtitle Frame Rate.

Tips for a clean conversion

Check that it is a text file. Open the .sub in a text editor. Lines that start with {123}{456} are MicroDVD. Unreadable symbols mean VobSub, a picture format this tool can’t read.

Check accented letters. MicroDVD files are old, and many are saved in a Windows code page. If letters look wrong in the preview, pick the right encoding next to the file name, or repair the file with Fix Subtitle Encoding. The .srt is always saved as UTF-8.

Name the file after the video. A file called movie.srt next to movie.mkv is picked up automatically by VLC, Plex, Jellyfin and most TVs.

Frequently asked questions

What is a MicroDVD .sub file?

MicroDVD is an old text subtitle format. Each line holds a start frame and an end frame in curly brackets, then the text, like {75}{131}Is this seat taken? It counts video frames instead of hours, minutes and seconds.

Why are my subtitles more and more out of sync after converting?

The frame rate is wrong. Frames only become times once you know how many frames the video shows per second. If the subtitles start right and drift later, pick the frame rate of your video next to the file name, usually 23.976, 24 or 25, and the times are worked out again.

How do I know the frame rate of my video?

Some .sub files state it on their first line, and the tool reads it from there. Otherwise open the video in your player and look at its media information; VLC shows it under Tools, Codec Information. A film from a Blu-ray is usually 23.976, a European TV recording 25.

Can this convert the .sub file that came with an .idx file?

No. A .sub next to an .idx file is VobSub, which stores each subtitle as a picture, not as text. There is nothing to read in it without recognising the letters first, so the tool refuses it. Only text .sub files in the MicroDVD format can be converted.

Is anything lost when converting SUB to SRT?

Line breaks, italic, bold and underline are kept. Colours, fonts and positions have no place in SubRip, so they are removed and counted in a notice above the Download button.

Are my subtitle files uploaded anywhere?

No. The file is read and converted by JavaScript in this browser tab. It never leaves your device, and the tool keeps working if you go offline after the page has loaded.

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