Summary
- Most rejected subtitle files fail on a short list: malformed timecodes, overlapping cues, lines that are too long, cues that are too fast to read, and garbled characters.
- Find the problems first. A validator reports each one by cue number. Then repair the ones that can be fixed safely, and fix wording by hand.
- VideoText's checks use 42 characters per line and 20 characters per second. If your client's spec sets different limits, their spec wins.
A rejection email rarely says exactly what failed. "Doesn't meet spec" or "failed QC" could mean a single malformed line or a reading-speed problem across hundreds of cues. The quickest way back is to find every issue at once, fix what can be fixed safely, and resend with confidence.
Step 1: read the client's spec
Before touching the file, find the numbers you are being measured against:
| Spec item |
What to write down |
| Characters per line (CPL) |
The maximum per line |
| Lines per cue |
The maximum number of lines |
| Reading speed (CPS) |
The maximum characters per second |
| Cue duration |
Minimum and maximum time on screen |
| Gap between cues |
Any minimum gap, in frames or milliseconds |
| Format |
SRT or WebVTT, and any encoding requirement |
Limits vary by client and platform. Our CPL and CPS benchmarks by style guide collects published figures.
Step 2: find every problem at once
Run the file through the subtitle validator. It needs no account, runs in your browser so the file is not uploaded, and accepts SRT and VTT up to 20 MB. It reports problems with their line or cue number:
- Structure: unreadable timing lines, a dot instead of a comma in SRT timestamps, missing hours, missing blank lines between cues, wrong or repeated cue numbers, empty cues.
- Timing: cues that end before they start, overlapping cues, cues out of order, tiny gaps that make captions blink.
- Readability: lines over 42 characters, cues over 20 characters per second, and cues shown for under 0.8 seconds.
- Encoding: garbled accents such as "é" for "é", which can be recovered, and characters already lost as "�", which cannot.
Step 3: fix what can be fixed safely
For structure problems, the validator's one-click repair handles the safe SRT fixes. For timing and layout, use Fix Subtitles. Per its product page, with Fix timing and line breaks on (the defaults):
| Problem |
What Fix Subtitles does |
| Overlapping cues |
Ends a cue before the next one starts |
| Cue ends at or before its start |
Gives it an end time after the start |
| Whole file early or late |
Moves every cue by a fixed number of milliseconds |
| Long lines |
Re-wraps at word boundaries onto at most two lines of 42 characters; splits the cue if it still doesn't fit |
| Fast cues |
Gives cues over 20 characters per second more time where the next cue allows, up to 10 seconds per cue |
Anything it cannot repair safely is listed with its location for you to fix by hand. A single word longer than the line limit, for example, is left as it is and reported. Your original file is never changed. Every check and threshold is documented in the Fix Subtitles checks reference.
Checking needs no account. A free account shows what it found and lets you fix and download; free SRT and VTT downloads carry two short VideoText watermark cues, one at the start and one after the last cue. For client delivery, Pro removes the watermark and adds cue editing and PDF/Word export. Pro is $14.99 a month or $120 a year; see VideoText pricing.
Step 4: fix what software can't
- Wording and translation. Fix Subtitles does not check whether the words or a translation are right.
- Timing that drifts. If cues slip further out of sync over the video, a fixed shift won't fix it. The free Subtitle Delay Fixer stretches the timing from two lines you can hear. See how to fix subtitle timing drift.
- Shot changes and client-specific rules such as italics for off-screen speech or forced narratives.
Step 5: re-check and resend
Run the repaired file through the validator again. Then reply to the client with a short note: what failed, what you changed, and that the file now passes their CPL and CPS limits. A clear note often matters as much as the fix.
Common causes by symptom
| Client says |
Likely cause |
Where to look |
| "File won't import" |
Malformed timecode, dot instead of comma, bad numbering |
Validator, structure section, or Fix SRT File |
| "Captions flicker" |
Overlaps or tiny gaps |
Validator, timing section, or Fix Overlapping Subtitles |
| "Too much text on screen" |
CPL or line count over spec |
Fix Subtitles line breaks |
| "Viewers can't keep up" |
CPS over spec |
Fix Subtitles reading speed |
| "Strange characters" |
Encoding |
Validator, encoding section, or Fix Subtitle Encoding |
For player-side problems (an SRT that won't show in a media player or TV), our guide to SRT files that won't work covers nine causes.
FAQ
Why was my SRT rejected when it plays fine?
Players forgive a lot. Editors, platforms and QC tools are stricter, and one malformed line can stop a whole file from importing.
Can I fix subtitle errors without an account?
You can check an SRT or VTT in the validator with no account, and its one-click repair handles safe SRT structure fixes. Fixing timing and layout in Fix Subtitles needs a free account.
Does fixing change my original file?
No. Fix Subtitles gives you a new file and leaves the original unchanged.
What if the client's limit is 37 characters, not 42?
Fix Subtitles wraps to 42. If your client's limit is lower, use the report to find the cues that exceed it and adjust those by hand.
Next step
Before you reply to the rejection, check the file in the subtitle validator and see exactly what failed.
Sources: VideoText Subtitle Validator, https://videotext.io/tools/subtitle-validator, and Fix Subtitles, https://videotext.io/fix-subtitles (checked October 25, 2026).