TikTok Subtitles Best Practices: Font Size, Safe Zones and Display Time
Subtitles are not decoration you slap on and forget. With the same script, one font size step larger, a slightly higher position, or a few extra characters per caption completely changes the viewing experience. This article breaks down the key parameters of TikTok subtitles so you can adjust them directly.
Safe Zones: Where the UI Covers Your Text
TikTok plays vertically in full screen, with UI elements layered right on top of the picture. Placing subtitles in these areas is the same as not placing them at all:
- Bottom: account name, video caption, music bar and bottom navigation
- Right side: a whole column of buttons — profile, like, comment, share, save
- Top: the search entry and the "Following / For You" switch
The common practice is to keep key content in the middle of the frame: leave about 20% of the height at the bottom, about 15% of the width on the right, and about 10% at the top. The horizontal position of subtitles does not need changing; the vertical position needs to move up overall.
The self-check is simple: play the finished video full screen on a phone, pause on the lowest subtitle line, and see whether it is covered by the caption or any button.
Font Size: How Much of the Frame Height
The rule of thumb is a single-line font size of 1/30 to 1/22 of the frame height — on 1080×1920 vertical footage, that is roughly 64–88 px. Two easily missed points:
- Count both lines for two-line subtitles, and keep the whole subtitle block within 1/6 of the frame height.
- Landscape footage needs a higher ratio. When landscape video plays on a phone, the picture is smaller overall, so subtitles at the same ratio also look smaller.
Caption Length and Display Time
Display time must match the character count, otherwise viewers get cut off mid-read. Industry rules of thumb for subtitles:
| Language | Comfortable reading speed | Per-caption limit |
|---|---|---|
| Chinese | 4–6 characters per second | 8 characters per second |
| English | 12–17 characters per second | 20 characters per second |
Two more hard constraints: each caption should be no shorter than 1 second and no longer than 6 seconds; beyond 6 seconds usually means the sentence should have been split into two captions.
The most common mistake is refusing to break the sentence — cramming a whole spoken line into one caption. Better to cut an extra caption than make viewers chase the text.
Two-Line Bilingual Layout: The Trade-offs
Bilingual subtitles carry more information, but the width of a vertical frame does not change. Three principles:
- Fix the language order first. If your audience is mainly Chinese-speaking, Chinese goes on top; if mainly international, the translation goes on top. Whatever you choose, keep it consistent across the whole video.
- Size for the longer line. The same sentence written in English usually takes more width than in Chinese. Set the font size by the wider line, otherwise the English wraps and two lines become three.
- If it does not fit, split the caption — do not shrink the font. Showing it as two consecutive captions beats squeezing the font down to unreadable.
The least effortful way to make bilingual subtitles is to first get an "original + translation" subtitle file from the bilingual SRT generator, then import it into your editor and adjust styling — font size, position and timeline all remain editable, which is far cheaper than reworking the finished video.
The Four Most Common Mistakes
| Mistake | Symptom | Fix |
|---|---|---|
| Subtitles covered by the UI | Bottom text pressed under the caption or navigation | Move the subtitle line up overall, leave about 20% at the bottom |
| Single caption too long | Viewers swipe away halfway through reading | Split captions at 4–6 characters per second |
| Insufficient color contrast | White text unreadable on a bright background | Add an outline or shadow, or back the text with a semi-transparent bar |
| Timeline offset | Subtitles arrive early or late relative to the speech | Check cue by cue, do not align only the beginning |
FAQ
Where is the safest position for TikTok subtitles?
Keep them in the middle-to-upper area of the frame: about 20% clear at the bottom to avoid the caption and navigation, and clear of the roughly 15%-wide button column on the right. The most reliable check is still playing it full screen on a phone.
How big should the subtitle font be?
Single-line font size at 1/30 to 1/22 of the frame height — about 64–88 px on 1080×1920 vertical footage. For two-line bilingual subtitles, step down one size and keep the whole block within 1/6 of the frame height.
How many characters per caption?
Within 12–15 characters for Chinese and 32–38 characters for English, while also matching the reading speeds of 4–6 Chinese characters or 12–17 English characters per second. When the two conditions conflict, the reading speed wins — better to split into another caption.
Will two bilingual lines block the picture?
There is a risk, but it is manageable. Do not enlarge both lines at once: set the font size by the longer line first, then confirm the whole subtitle block stays within 1/6 of the frame height. If it genuinely does not fit, split the bilingual pair into two consecutive captions instead of shrinking the font further.