Subtitle (SRT) Fixer & Line Checker
Fix broken SRT files and check characters per line, lines per caption and reading speed. Repair timestamps, overlaps and numbering in one click. Free and private.
Captions
0
in your file
Issues found
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in your original file
Left after fixes
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in the fixed file
| # | Time | Lines | Longest line | Chars/sec | Issues |
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Everything runs in your browser. Your subtitles are never uploaded. Issues that need a human, such as reading speed or very short captions, are listed but not changed.
What Is an SRT Subtitle Fixer?
An SRT subtitle fixer repairs the small errors that stop a subtitle file from playing correctly. SRT is a plain text format, so it is easy to edit but also easy to break. A wrong timestamp, a missing number or two captions that overlap can make a player skip lines or reject the file.
This tool fixes those problems for you and also works as a subtitle character and line checker. It counts the characters in every line, flags captions that are too long, and shows which captions are read too fast.
How to Fix an SRT File Online
- Paste your subtitles into the left box, or upload a .srt file.
- Set your limits for characters per line, lines per caption and reading speed.
- Choose the fixes you want, such as auto-wrap, overlap repair and sorting.
- Check the table to see every caption that has an issue.
- Copy the fixed text or download it as a .srt file.
Results update as you type, so you can change a setting and see the effect immediately.
What the Line and Character Checker Tests
The checker looks at every caption in your original file and lists the problems it finds:
- Line too long: a line has more characters than your limit. Tags such as <i> are not counted.
- Too many lines: a caption has more lines than your limit.
- Too fast: the reading speed in characters per second is above your limit.
- Under 1 s or over 7 s: the caption is on screen for too short or too long a time.
- Overlaps next: the caption ends after the next one starts.
- End before start: the end time is earlier than the start time.
- Empty text or unreadable timestamp: the caption has no text, or its time cannot be understood.
Common SRT Errors This Tool Repairs
- Wrong time format. Times written as 00:00:01.500, 0:0:1,5 or 01:02,500 are rewritten as 00:00:01,500 style times.
- Wrong numbering. Captions are renumbered from 1 in the right order, even if the original numbers were missing or repeated.
- Out of order captions. With sorting on, captions are placed by start time.
- Overlapping captions. The end time is moved back to the start of the next caption.
- Long lines. Text is re-wrapped into balanced lines that fit your limit.
- Extra spaces and empty captions. Spaces are trimmed and empty captions are removed.
- Repeated captions. Identical neighbouring captions can be merged into one.
Recommended Characters per Line and Reading Speed
There is no single rule, but many streaming and broadcast style guides use limits close to these:
- Characters per line: about 42 for most Latin-script languages.
- Lines per caption: two, with a short caption on one line whenever possible.
- Reading speed: around 17 to 20 characters per second for adult audiences, and lower for children.
- Duration: at least about one second and at most about seven seconds on screen.
Always check the guidelines of the platform you publish on, because limits can differ by language and by client. You can change every limit in the tool to match them.
The SRT Format Explained
An SRT file is a list of captions separated by blank lines. Each caption has three parts: a number, a time line and one or more lines of text.
For example, a caption has the number 1, then the time line 00:00:01,000 –> 00:00:03,500, then the text Hello and welcome. Times use hours, minutes, seconds and milliseconds, with a comma before the milliseconds. The arrow is two hyphens and a greater than sign.
Shift Subtitle Timing to Fix Sync Problems
If your subtitles appear too early or too late for the whole video, use the Shift all times box. Enter a positive number of milliseconds to delay every caption, or a negative number to show them earlier. For example, 1500 delays all captions by one and a half seconds. This fixes a constant offset, but it cannot fix subtitles whose speed drifts over time.
Tips for Better Subtitles
- Break lines at natural pauses, not in the middle of a phrase.
- Keep each caption to one idea whenever you can.
- Leave a small gap between captions so the eye can register the change.
- Use a dash at the start of each line when two people speak in one caption.
- Read the result aloud against the video. A checker finds technical errors, but only a person can judge the wording.
Is It Safe to Fix Subtitles Online?
Yes. All the work happens in your browser. Your subtitle text is not uploaded, stored or shared, so you can safely use it for private or unreleased videos.
Frequently Asked Questions
How do I fix an SRT file?
Paste the text or upload the .srt file, choose your limits and fixes, and copy or download the result. The tool repairs timestamps, numbering, order, overlaps and long lines.
How many characters per line should subtitles have?
Many style guides use about 42 characters per line with a maximum of two lines. You can set any limit in the tool to match your platform.
What is a good subtitle reading speed?
Around 17 to 20 characters per second is common for adult audiences. Captions above your limit are marked Too fast in the checker.
Can this tool sync subtitles that are late or early?
Yes, if the delay is constant. Enter the offset in milliseconds in the Shift all times box. It cannot fix subtitles that slowly drift out of sync.
Why does my subtitle file not play?
Common causes are a wrong time format, a missing blank line between captions, a wrong number or an overlap. Paste the file here and the checker will show the captions that have problems.
Does it work with languages such as Arabic, Bangla or Chinese?
Yes, any text is accepted. The line limit counts characters, so for languages where characters are wider or narrower than Latin letters, adjust the limit to suit.
Does it change my subtitle text?
The wording is never changed. The tool only fixes numbering and times, trims spaces and re-wraps lines. Turn off auto-wrap if you want to keep your own line breaks.
Is my subtitle file uploaded to a server?
No. Everything runs in your browser, and your file never leaves your device.