What is the best font size for video captions?
Roughly half your audience watches on mute, so your captions are the video. Here are concrete size targets for YouTube, TikTok and Reels, the safe-zone rules that keep text on screen, and the one test that beats any number.
By Thomas, founder of CutScore · Updated June 2026
There is no single magic number, and that is exactly why people keep searching for one. A caption that looks perfectly readable on your 27-inch monitor can turn into mouse type on a phone, on a bus, in the sun. The size that works is not measured in points. It is measured as a share of the frame, because that is the only thing that stays constant when your video gets watched at every size from a watch to a TV.
I learned this the slow way. Early on I shipped a tutorial with captions I had set in points, judged at 100 percent zoom on a big screen, and felt very pleased with myself. Then I watched it back on my phone the next morning and could barely read my own words. The text was technically there. It was just too small to be useful, which for a muted viewer is the same as not being there at all.
So the real question is not "what point size." It is "what percentage of the frame, and is it still readable on the smallest screen anyone will use." Get those two right and the point number sorts itself out. Here are the targets.
The best font size for captions, by platform.
Think in percentage of frame height first, then convert to pixels and points for your editor. These are starting points you confirm with the arm's-length test, not laws.
| Where it plays | Frame | Caption cap height to aim for | Roughly |
|---|---|---|---|
| YouTube · horizontal | 1920 × 1080 | ~44–54 px (4–5%) | 32–42 pt in most editors |
| YouTube · 4K master | 3840 × 2160 | ~88–108 px (4–5%) | scale up with the frame |
| Shorts / TikTok / Reels | 1080 × 1920 | ~70–100 px | the chunky look you already see |
| Square feed post | 1080 × 1080 | ~48–64 px | slightly bigger than 16:9 |
Measuring caption size as a share of the frame on every clip gets old fast. CutScore reads it for you and flags the exact moments where text is too small, too low-contrast, or out of the safe zone.
Four things that decide if captions actually read.
1. Size as a percentage, set on the smallest screen
Pick your target from the table, then judge it at the size a real viewer uses. Not your editing monitor at 50 percent zoom, where everything looks generous. The cleanest habit is to size captions to about 4 to 5 percent of frame height and then immediately preview on a phone. If your editor shows percentage of frame, use it. If it only shows points, set the size once, export a ten-second test, and read it on your phone before you commit to the whole video. This habit fixes most caption problems before they exist, and it is a big part of what we analyze.
2. Contrast, because size cannot save thin grey text
A perfectly sized caption still fails if it blends into the background. White text with a dark outline or a semi-transparent box behind it stays readable over almost anything, including a bright sky or a busy room. Thin grey captions on a light background are the classic mistake, and bumping the size does not fix them. If you want to be precise about it, run a quick text contrast check on your most cluttered shots, not your cleanest one.
3. Lines on screen, because nobody reads a paragraph that flashes by
Big text means fewer words fit, and that is a feature. Keep one or two short lines on screen at a time. A caption that wraps onto four lines is not readable no matter how clean the font is, because it scrolls away before the eye finishes line two. If a sentence is long, break it across two caption cards rather than shrinking the font to cram it in. Two readable lines always beat one giant line that covers the speaker's face.
4. Safe zone, so the size you chose survives the platform
You can nail the size and still lose, if the caption sits where the app paints its own buttons. On a vertical short, the bottom fifth of the frame is a war zone of like counts, share icons, and the caption text the platform adds. Park your burned-in captions above that, in the lower-middle of the frame, and check the safe zones for Shorts for the exact margins. A 90-pixel caption hidden behind a share button is a 0-pixel caption, as far as the viewer is concerned.
Here is a real CutScore coaching report for an everyday video: caption size, contrast and safe-zone placement scored, with timestamps and the exact fixes.
If you only fix three things about your captions.
Most of the jump from "I can barely read this" to "clean and obvious" comes from these three. Fix them first.
By eye, by ruler, or in one pass.
By eye, on a phone
Free, and the most useful test there is. Export the video, watch it on a phone held at arm's length in a bright room, and read every caption at a glance. If you slow down or squint, the text is too small, too thin, or too low-contrast. The catch is you have to be honest with yourself.
By measuring the frame
Accurate and a little tedious. Drop a guide at 5 percent of frame height and match your cap height to it, then confirm the caption sits inside the safe zone. It works, but you are doing it on every clip, in every aspect ratio, by hand. Great if you like precision. Most people drift.
With a coach in one pass
Hand the file (or a link) to CutScore. It measures caption size as a share of the frame, checks contrast and safe-zone placement, and gives you a 0 to 100 score with timestamped evidence and the fixes. No guides to drop. See a sample report.
Frequently asked.
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