Caption length and safe-zone checker for vertical video
Type the text you plan to burn into a vertical video. See how it wraps, how many lines it takes, and where it lands against adjustable safe-zone margins.
Your caption
Safe-zone margins
A conservative rule of thumb, not an official spec. Each app draws its buttons, names and captions in different places and changes them over time.
Preview (9:16)
Yellow box: the area left after the margins. Keep text inside it.
Reelsmith accepts up to 120 characters per scene caption and wraps it at the widths above, so this preview matches what it renders. Up to 12 scenes per video.
Questions and answers
How long should an on-screen caption be?
Short enough to read before the scene ends. Two or three short lines per scene usually works; this page shows the line count so you can split long sentences across scenes.
Are these safe-zone margins official?
No. Platforms don’t publish one fixed safe zone for organic Reels, TikToks or Shorts, and their on-screen buttons move. The defaults are a cautious rule of thumb you can adjust; always check a preview in each app.
Does the caption I type get saved?
No. Everything runs in your browser and nothing is sent to our servers.