What Is the Subtitle Length Checker?
The Subtitle Length Checker analyzes subtitle text line by line and flags any lines that exceed a configurable character limit. The broadcasting and streaming industry generally recommends keeping subtitle lines between 15 and 20 characters for comfortable on-screen readability. Longer lines get cut off, wrap awkwardly, or force viewers to read faster than they can process. This tool shows you exactly which lines need trimming.
Subtitles are not regular text. They compete with visual content for the viewer's attention and appear on screen for only a few seconds. Research in subtitle readability consistently shows that shorter lines — roughly 15 to 20 characters — allow viewers to absorb the text in a single glance without losing track of the video. When lines exceed this range, comprehension drops, especially for non-native speakers and hearing-impaired viewers who rely entirely on the text.
The tool processes your text entirely in the browser. Paste your subtitle script, and it immediately splits the text by line breaks, counts characters per line, and color-codes each line: green for 15 characters or fewer, yellow for 16 to 20, and red for anything over 20. A summary panel shows total lines, average character count, and the number of lines exceeding the limit. Adjust the maximum character threshold if your project has different requirements.