SRT Validator
Check subtitle files for format errors, timing problems and readability before you publish or deliver them. The validator explains every issue, gives a verdict and can download a fixed file.
- Clear verdict
- Batch: 50 files
- Never uploaded
- Free
Drop subtitle files here
or
SRT · VTT · ASS / SSA · SBV · SUB · TTML · LRC · TXT
Your subtitles are processed on your device and are never uploaded.
No subtitles match the current search or filter.
Next: SRT Formatter Subtitle Duration Fixer Subtitle Line Breaker
How to validate an SRT file
A full check takes a few seconds.
- 1
Add your files
Drop up to 50 subtitle files or paste the text. SRT, WebVTT, ASS and other formats are checked.
- 2
Choose a standard
Pick Netflix, BBC, TED or ARD/ZDF, or enter custom limits for reading speed, line length, duration and gap.
- 3
Review and fix
Read the verdict, click an issue type to filter the list, then download the fixed file or the CSV report.
What the SRT validator checks
Syntax, timing and readability in one report.
Errors
End time not after start, overlaps with milliseconds, wrong order, empty subtitles, unclosed tags.
Warnings
Duration too short or too long, reading speed too high, long lines, too many lines, small gaps.
Format checks
Missing WEBVTT header, numbering out of sequence, non-standard timecodes, missing blank lines.
Encoding check
Finds broken characters from a wrong encoding and reports files that are not UTF-8.
Standard or custom limits
Limits come from a preset such as Netflix, BBC, TED or ARD/ZDF, or from your own values.
Filter by issue
Click an issue type to see only the subtitles affected by it.
Download fixed file
One click cleans text and tags, fixes timing and optionally re-breaks long lines.
CSV report
Download the findings as a CSV file to share with a client or colleague.
What makes an SRT file valid?
SubRip was never formally standardized, but players agree on the basics. A valid block has a number, a timecode line in the form 00:01:02,500 --> 00:01:05,000, at least one line of text and a blank line after it. The end time must be later than the start, subtitles should follow each other in order, and two subtitles should not be on screen at the same moment. An SRT validator checks every block against these rules.
Many problems are invisible in a text editor. A file saved as Windows-1252 and read as UTF-8 shows broken characters in place of accented letters. Timecodes with a dot instead of the comma, or with missing digits, work in forgiving players and fail in strict ones. A WebVTT file without the WEBVTT header on its first line is rejected by browsers. The validator reports these cases as errors or warnings, together with the subtitle concerned.
Beyond syntax, the tool can check subtitle quality against a delivery standard. Netflix asks for at most 42 characters per line, two lines, 20 characters per second, a minimum duration of 5/6 second, a maximum of 7 seconds and a gap of at least 2 frames. The BBC and German-language broadcasters use 37 characters per line. Choose a preset or enter custom limits, and every subtitle outside them is listed as a warning.
Severity levels in the report
| Level | Examples | What it means |
|---|---|---|
| Error | End not after start, overlap, wrong order, empty subtitle, unclosed tag, broken characters | The file may be rejected or displayed incorrectly |
| Warning (readability) | CPS too high, line too long, too many lines, duration too short or too long, gap too small | The file plays, but breaks the chosen standard |
| Warning (format) | Not UTF-8, numbering out of sequence, dot instead of comma, missing blank lines, mixed line endings | Tolerant players cope, strict software may not |
| Hint | Extra spaces, credits or ads, repeated subtitle | Cosmetic issues worth cleaning up |
Tips
- For full control over the cleanup instead of the one-click fix, use the SRT Formatter.
- Many reading-speed warnings? The Subtitle Duration Fixer extends fast subtitles as far as the next subtitle allows.
- Single wrong times and overlaps are quickest to correct by hand in the SRT Editor.
- Validate again after every conversion. The Subtitle CPS Calculator shows the distribution of reading speeds in more detail.
Frequently asked questions
Can’t find your answer? Contact us — we reply quickly.
How do I check whether an SRT file is valid?
Drop it on this page. The SRT validator reports errors, warnings and hints and gives one of three verdicts: Valid, Valid with warnings, or Problems found.
Why does my SRT file not work on my TV or in my video editor?
Typical causes are an encoding other than UTF-8, timecodes with a dot instead of a comma, missing blank lines or overlapping subtitles. The validator finds all of these and can download a fixed file.
What does the one-click fix change?
“Download fixed file” cleans text and tags and fixes timing; re-breaking long lines is optional. The original file on your device is not modified.
Can I validate WebVTT files too?
Yes. WebVTT, ASS/SSA, SBV, TTML and other formats are read, and for WebVTT the validator also checks that the WEBVTT header is present.
Which limits are used for reading speed and line length?
Those of the selected standard, for example 20 CPS and 42 characters per line for Netflix or 37 characters for the BBC. Custom values can be entered instead.
Are my files uploaded for the check?
No. Validation runs in your browser and the files are never uploaded.
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