Subtitle reading speed checker
Open or paste an .srt or .vtt file to see, caption by caption, how fast it reads: characters per second, the longest line, the number of lines, how long it stays on screen, and whether it runs into the next caption.
Pick a preset or set your own limits, then show only the captions that break them. Everything runs in your browser; the file is never uploaded.
Making captions for a new video? The video caption generator matches captions to the speech, lets you choose how much text shows at once, and exports SRT or VTT.
Make captions from a videoWant these captions spoken? The free plan includes 25,000 characters a month, no card needed. Paste the text into the editor after you sign in.
How to check subtitle reading speed
- 1
Open an .srt or .vtt file, or paste its contents.
- 2
Choose 17 or 20 characters per second, or set your own limits for line length, lines and duration.
- 3
Read the summary, then filter the table to the captions that need work.
- 4
Fix those captions in your subtitle editor: split long ones, trim words or give them more time.
Good to know
How characters are counted
Every character you would see on screen counts, letters, spaces and punctuation included. Formatting tags, position codes and line breaks do not, and an accented letter or an emoji counts as one.
Limits are guidance
The presets follow common guidance for adult viewers: 17 or 20 characters per second, 42 characters per line, 2 lines, and 0.83 to 7 seconds on screen. Standards vary by platform, broadcaster, language and audience.
Overlapping captions
A caption overlaps when it is still on screen after the next one starts. Players handle that differently, and some stack both captions, so many delivery specifications ask for a small gap instead.
Captions that cannot be measured
Captions that end at or before they start are listed with the line number of their timing, and captions with a timing but no text are counted. Neither has a reading speed, so neither is in the table.
Nothing leaves your device
The file is read and checked in your browser. It is not uploaded to our servers or stored anywhere.
Questions, answered
What is a good reading speed for subtitles?
Common guidance for adult viewers sits between 17 and 20 characters per second, and children's programmes usually allow less. Standards vary by platform, broadcaster and language, so use the one you are delivering to.
How is characters per second calculated?
Divide the characters on screen by the time the caption is shown. A caption of 40 characters shown for 2.5 seconds reads at 16 characters per second.
How many characters fit on one subtitle line?
42 characters per line, on no more than 2 lines, is common guidance for languages written in the Latin alphabet. Some languages and platforms use shorter lines, so treat it as a starting point.
How long should a subtitle stay on screen?
Common guidance is at least about 0.83 seconds and no more than 7. Shorter captions flash past before they can be read; longer ones tend to stay up after the line has been spoken.
Does it check WebVTT files too?
Yes. WebVTT headers, NOTE, STYLE and REGION blocks and cue settings are read and set aside; the caption text and timing are what get measured.
Is my subtitle file uploaded?
No. It is read and checked in your browser and is not sent to our servers or stored.