How to Size Video Subtitle Fonts
The same subtitle font size reads very differently depending on video resolution and viewing distance. This calculator takes your resolution and viewing distance and returns a minimum subtitle font size (px) that stays comfortably readable on screen.
How It's Calculated
The baseline is about 4.5% of the video's vertical resolution, scaled up proportionally once viewing distance exceeds a 5ft (150cm) baseline. As resolution increases, the pixel value must grow too in order to preserve the same visual size on screen.
Applying It in Practice
Close-viewing contexts like mobile phones and far-viewing contexts like TVs call for different baselines. Adding a semi-transparent background box or a text stroke behind subtitles further improves readability over bright backgrounds. If you're publishing to multiple platforms, calculate the value separately using each platform's typical viewing distance.
Frequently Asked Questions
Yes. As viewing distance increases beyond about 5ft (150cm), subtitles need to scale up to stay readable. This calculator increases the recommended size proportionally with distance.
To keep the same visual size on screen, the pixel value must scale with resolution. That's why 4K needs a larger px value than 1080p even though the perceived size stays the same.