How Many Words Should a Caption Line Have?

For short-form vertical video, two to four words per caption line reads best, with one line on screen at a time; for long-form or horizontal video, follow broadcast rules of up to about 42 characters per line and no more than two lines. Shorter lines can be read in a single glance, which matters when people are scrolling with the sound off.

Why short lines work on short-form

• Phones are narrow. A vertical frame holds fewer large words across.
• Big text needs room. Captions on TikTok and Reels are large so they're readable at arm's length.
• Speech is fast. Creators talk at 150–180+ words per minute; short lines keep up without walls of text.
• The eye follows the highlight. With word-by-word highlighting, short lines let the active word stand out.

Capsubs shows up to three words per line by default and starts a new line at the end of each sentence, so a line never mixes two sentences.

What the broadcast rules say

These were written for TV and streaming, but they're the best-tested guidance on readability:

The BBC also notes that the equivalent of 37 characters in a landscape frame is about 25 characters across a vertical 9:16 frame. With short-form's large fonts, that's usually 2–4 words.

Break lines at natural points

When a line has to break, break where a speaker would pause. The BBC, Netflix and DCMP all say the same things:

• Break after punctuation (full stop, comma, dash).
• Break before conjunctions ("and", "but") and prepositions ("on", "in").
• Don't separate an article from its noun ("the + table"), a first name from a last name, or a pronoun from its verb ("he + is").

Bad: "I went to | the store and" Good: "I went | to the store"

Timing tips

• Don't flash a line for less than about a third of a second per word.
• Bridge short gaps between lines so captions don't blink on and off.
• Start a new line after a pause in speech, even if the current line isn't full.

The free Script Timer counts how many caption lines a script makes at three words a line.

FAQ

Should captions be one word at a time? One-word captions are punchy for hooks but tiring for a whole video. Two to three words is the usual sweet spot.

Two lines or one? On short-form, one line. On horizontal video, two lines are fine.

Can I change words per line in Capsubs? The dashboard uses three; developers on Pro can set max_words_per_line from 1 to 10 through the API.