Check every subtitle against reading-speed rules. See characters per second, line length and duration, with lines that break Netflix or BBC limits highlighted.
Free and unlimited. Your file never leaves your browser.
How It Works
Choose a file or paste its contents. It is read in your browser, not uploaded.
Adjust the settings for this tool, if it has any.
Download the new file, or copy it to your clipboard.
The Subtitle Reading Speed Checker is a free online tool from ShortsHero: flag lines viewers can't read in time. It runs entirely in your browser, so the file is never uploaded and the result is instant. Free, with no account.
Everything happens in your browser: the file is never uploaded, which also makes it instant.
Why Use This Tool
The file is read in your browser. Nothing is uploaded to a server.
No upload and no queue, so even a feature-length file takes a moment.
Accepts mislabelled files, either decimal separator and stray formatting.
Writes the format exactly as players and editors expect it.
Yes, free and unlimited. It runs in your browser, so there is nothing to sign up for and nothing is uploaded.
No. The file is read and written by JavaScript in this tab. You can disconnect from the internet after the page loads and it still works.
The parser skips blocks it cannot read and keeps everything else. Run the file through our SRT validator afterwards to see what was wrong.
ShortsHero turns long videos into short vertical clips with AI moment detection, face tracking and animated captions — and has free tools for subtitles, transcripts and video formats.
The same transcription powers ShortsHero's clip maker: it finds the strongest moments, reframes them to vertical and adds word-by-word captions in 36 styles.
Try the clip maker freeFree to start · No credit card required
Keep Going
Validate an SRT file before upload. Finds overlapping cues, bad timestamps, missing numbers and blank lines, then fixes them in one click so YouTube accepts it.
Subtitles showing weird symbols instead of letters? Re-encode your SRT to UTF-8 and fix Arabic, Hebrew, Cyrillic, Greek and accented characters instantly.
Strip hearing-impaired tags from subtitles. Removes [music], (laughs), speaker names and sound cues from SRT or VTT files so only the dialogue remains.
Sync lyrics to a song automatically. Upload the track and paste the lyrics, AI times every line, then export SRT or LRC for lyric videos and karaoke.
Make karaoke subtitles with word-by-word timing. Exports an ASS file with karaoke tags that fill each word as it is sung or spoken. Works in VLC and Aegisub.
Spell-check an SRT or VTT file in your browser. Every typo, repeated word and odd capital is flagged with a one-click fix, and timing stays as it was.
Runs entirely in your browser. Your file is never uploaded.