3 Attributes of a Great Captions and Subtitles Font

Captioning and subtitling have changed dramatically since the days of set-top decoder boxes and optical burning to celluloid. Online video platforms, in particular, have made them much more cost-effective to produce and to deliver to ever-increasing audiences. But the principal drive for these services remains the same – making content accessible to audiences who otherwise wouldn’t be able to take it in. And fonts – the way that the captions and subs text looks, effectively – can have a huge impact on their accessibility.

This post will list the three attributes that make certain fonts ideal for captions or subtitles localization projects.

[Average read time: 4 minutes]

Think accessibility

Two notes before we start. First, while this advice is most pertinent to projects that require open captions or burned-in subs, they’re also good to keep in mind when your deliverables are text files to be incorporated into video players, since sometimes default font settings can be applied to them. Second, this will be a general informational post, not a prescription for your video translation or captioning project. While the tips that follow are generally sound advice, each project has very specific requirements and specifications, and must balance concerns of aesthetics and accessibility.

With that in mind, following are the three attributes of a great caption/subtitle font.

1. Legibility

Captions and subs text has a moving image behind it, one that can shift color 24 or more times per second, and move or change in ways that are disorienting to the eye. The text must stand out from all this activity – and this is no small feat. After all, white text will become nearly invisible in front of a white section of the image, while black text will do the same during dark scenes – but these are by far the easiest colors for human beings to read text in.

There are many ways to deal with this, including adding an outline to the text (for example, a thin black border over white text), or better yet, adding a background, as discussed in our previous post, 3 times when subtitles background boxes are great for localization. As effective as these solutions are, the font used itself has the most impact on legibility.

There are two main factors that make fonts legible on-screen. First, that they’ve incorporated screen versions into their font file. Many fonts have done this (certainly the most common ones), but several legacy fonts – especially ones created with an eye to print applications – haven’t added this functionality. These fonts can look ragged when used for video applications, especially when they’re compressed.

Second, the “look” of the font itself has a big effect on legibility. Fonts with consistent character widths and no serifs outline better. Thicker outlines can be applied, which then don’t “bunch up” at the thinner points in the font, which are usually at the serifs, as you can see in the following example:

But there’s more – sans serif fonts also stand out better from video content in general, mainly because they retain their shape visually against movement. Serifs can flutter visually against a digital image, especially animations with hard black and white lines. All of this may seem counter-intuitive to designers accustomed to print production, since serif fonts are generally believed to increase ease-of-reading in print – but against a moving video image, those serifs become a liability.

2. Readability

This attribute is closely related to legibility, but it focuses on how quickly the user can read through the text, as opposed to being able to tell it apart from the image in the background. Being able to read caption and subtitle text in the time allotted – that is to say, the amount of time that each chunk of text is visible on screen, before it fades out – is essential to their usability. If a viewer can’t make it through the content, they’re not going to engage with the video. That’s why there are character limits and time requirements for accessibility – and also why it’s important to consider a font’s readability.

So what makes fonts readable? When they’re in front of a video, two things. First, simplicity and standardization. Most people are accustomed to reading standard block fonts, which are generally pretty simple, like Arial, Helvetica, or Verdana. Non-standard fonts, even ones with a pleasing aesthetic, can take longer to read, as users mentally separate aesthetic embellishments from actual letters. The following example gives a drastic illustration of this:

Note that while the font on the left looks amazing, it’s hard to make out some words – “readers” in particular.

Other considerations include character width (wider characters require more visual scanning), character spacing (properly-spaced characters have better visual flow), and differentiation (like making sure that capital “i” and lower-case “l” are distinct). While these attributes are barely noticeable on single lines, they make a big impact on eyestrain – after all, if you’re using captioning or subtitling, one hour of television can mean reading 6,000 words or more, and all that reading adds up.

3. Symbol and character support

On a more technical level, it’s crucial to choose fonts that will support your project’s technical and language requirements. Remember that captions and SDH (subtitles for the deaf and hearing-impaired) also require symbols occasionally, most notably musical notes (the symbol ♫) when the text corresponds to lyrics in a song – it’s good to pick fonts that include it. Likewise, if possible, pick a font that has full Unicode language support, including Asian double-byte and right-to-left languages, if they’re part of your set. This is particularly true for corporate and e-Learning translation, which retains many English-language source words or names in Latin characters. Chinese subtitling for corporate videos, for example, requires a font with good support for both Chinese and Latin characters – and not all fonts have this.

Test before starting localization

Again, these aren’t hard-and-fast rules. Every project requires a different balance of aesthetics and accessibility. And it’s good to remember that aesthetics can add to the enjoyment of a captioned or subtitled video – especially for more creative content like online marketing videos, quirky shows, or even some non-traditional e-Learning. If you do decide to use a custom or non-standard font, just be sure to test it out on your video – and not just on the high definition (HD) version of your video, but on the lower-resolution versions that will be viewed on phones, DVDs or any other compressed media. Ask someone to watch the video with the audio off, if possible – and make sure that he or she can process the content. This will require some time up front, but it will be worth it. In audio & video translation – and in all multimedia localization – proper preparation is the key to making sure projects stay on budget and on scope.