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Open Captions in Social Media Videos: What’s the Best Font Size?

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Many social media users now want to watch videos with the sound turned off. To capitalize on the “silent watching” trend, many content creators add open captions to their videos. If you want to increase your engagement and followers, you too should start adding open captions. You also have to consider the standard aspect ratio of videos in the platform for best readability.

With that said, here are the best font sizes for open captions in social media videos.

Facebook video with captions


Facebook supports various aspect ratios for videos. It’s also popular for both long and short videos.

Generally, this means that you can use a small font size for your open captions because both PC and mobile users are likely to enter full screen for long videos. For short videos, go for large and short open captions.

Here are the best font sizes for the most commonly used aspect ratios on Facebook:

  • 4:5: 16px – 24px
  • 16:9: 12px – 20px
  • 1.91:1: 10px – 16px
  • 9:16 (stories): 20px – 32px

Facebook Stories has a built-in text tool that you can use to add open captions. However, you can only set the font size with the “pinch feature.” This makes it extremely difficult to have a consistent font size. If you use this over a video-editing tool, use only 20-60 characters for each open caption. Make sure to adjust the size for readability and consistency.

Instagram video with captions


The best aspect ratios for videos on Instagram are 4:5 (feed videos) and 9:16 (stories, IGTV). Instagram mobile users prefer to watch vertical videos because the app can’t rotate to accommodate horizontal videos (5:4 and 16:9). This means that your open captions have to be big and short to fit in a vertical video.

Only video-editing software can set a specific font size for your open captions. The built-in Instagram font for captions only has a slider, which makes it hard to have a consistent font size.

The best font sizes for captions on Instagram are:

  • Feed videos: 16px – 24px
  • Stories: 20px – 32px
  • IGTV: 20px – 32px

If you’re using the built-in text tool, make sure that each open caption has 20-60 characters. Adjust the size of each open caption to be readable and consistent.

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Twitter video with captions


4:5, and 1:1 are the best aspect ratios on Twitter because Users usually scroll down their feed quickly and play short videos one after another.

Generally, it’s best to use short open captions with large font sizes. Smaller fonts are still viable since Twitter tends to upscale video uploads.?

Here are the best font sizes when adding captions on Twitter:

  • 4:5: 16px – 24px
  • 1:1: 10px – 20px

TikTok video with captions


TikTok videos are locked at either 9:16 or 1:1. Many prefer 9:16 because it fills up the entire screen for mobile users.

The ideal font size for your TikTok captions:

  • When using video-editing software, set the font size to 20px – 32px.
  • When using the built-in text tool, use 20-60 characters per open caption.

For best results, record your video with a 1080×1920 resolution. This makes your open captions much more readable, no matter what font size you use.

YouTube video with captionsYouTube

The standard aspect ratio for YouTube videos is 16:9. However, you can go with other formats like 1:1, 4:3, and 9:16. 1:1 and 9:16 are best for YouTube Shorts.

Like on Facebook, you’re free to use small or large sizes for your open captions. This is because it’s common for users to enter fullscreen for longer videos.

Shorts, on the other hand, are a different story. They’re basically YouTube’s own take on TikTok’s short video format. Hence, it’s best that you use short open captions with a large font size.

For reference, here are the best font sizes for open captions in YouTube videos:

  • 16:9: 12px – 24px
  • 9:16: 20px – 32px
  • 1:1: 16px – 20px
  • 4:3: 8px – 16px


Adding open captions is a surefire way to make your video content stand out – however, it’s a long and tiring process. If you want to focus more on your future projects, consider using a free transcription service to take care of your open captions for you.

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