Captions for social media videos: why they matter and how to add them

Why do social media videos need captions?

Social media videos need captions for two groups: people who are deaf or hard of hearing, and everyone watching with the sound off. LinkedIn strongly recommends captions on video ads because its videos autoplay without sound (LinkedIn Help), and X strongly recommends closed captions or text overlays (X Business).

Captions are a text version of the speech and any other sound needed to understand a video, synchronised with the audio, according to the W3C Web Accessibility Initiative. In its usage, subtitles translate the speech into another language, although some regions call both subtitles.

Captions are also an accessibility baseline. WCAG 2.2 success criterion 1.2.2 asks for captions for all prerecorded audio in synchronised media, at Level A, the first of WCAG’s three levels (W3C). Its intent is to let people who are deaf or hard of hearing watch video, with captions that carry the dialogue, who is speaking and meaningful sound effects.

Burned-in captions vs closed captions: which should you use?

Use burned-in captions when a video must read the same everywhere, and closed captions when viewers should control them. The trade-off is plain: burned-in captions cannot be switched off, resized or translated by the player, while closed captions need a player and a platform that show them.

WCAG defines open captions as captions that cannot be turned off, such as text embedded in the video, and closed captions as captions that can be turned on and off with some players (WCAG 2.2). Burned-in captions are open captions. Closed captions usually travel as a file, and the W3C names WebVTT as the most common caption format on the web, with SRT and TTML as others.

	Burned-in (open) captions	Closed captions
Where they live	In the picture	In a file, such as SRT or WebVTT, or added in the app
Viewer can switch them off	No	Yes
Viewer can change size or colour	No	On players that allow it, such as YouTube
Look	Designed with the film	The player’s style
Other languages	A separate video per language	One file per language, where the platform takes several
Needs player support	No	Yes
Counts for WCAG 1.2.2	Yes, when complete	Yes, when complete
Best for	Feeds watched on mute, ads, reposted clips	YouTube, courses, your own website, several languages

Bottom line: pick one kind per upload. Burned-in captions plus the platform’s own captions show the same words twice.

What do accessibility guidelines require for captions?

WCAG 2.2, the W3C’s standard for accessible web content, requires captions for all prerecorded audio in synchronised media at Level A. The one exception is a video that is itself an alternative to text on the page and clearly labelled as such. Open and closed captions both qualify, as long as they are complete.

• Both kinds count. The W3C lists open (always visible) captions and closed captions as sufficient techniques for 1.2.2.
• Complete means important sounds too. Captions that carry the dialogue but leave out important sounds fail 1.2.2 (failure F8), though simplifying speech to keep it readable is standard practice.
• Captions should not cover the picture. WCAG’s definition says they should not obscure or obstruct relevant information in the video.
• Automatic captions need checking. The W3C says automatically generated captions do not meet user needs or accessibility requirements unless they are confirmed to be fully accurate.
• Music-only videos are exempt. A video with no audio information needed to understand it, such as background music alone, needs no captions.

For layout, the W3C suggests one or two lines per caption, generally under 32 characters a line, with each new sentence on a new line. Where a sentence must break, break it at a natural phrase (W3C WAI).

What do YouTube, Instagram, TikTok, LinkedIn, Meta and X say about captions?

Every major platform supports captions, in different ways: YouTube and LinkedIn take caption files, Instagram and TikTok generate captions from the speech, and Meta’s Ads Manager does both. The table lists what each platform’s own help pages said when checked on 4 October 2026.

Platform	How captions get there	What the platform says
YouTube	A caption file, including SRT and WebVTT, or automatic captions	Automatic captions vary in quality, so review and edit them (YouTube Help); viewers can change caption font, colour, size and background (YouTube Help)
Instagram Reels	Automatic closed captions	Made with speech recognition and shown at the bottom when turned on (Instagram Help Centre)
TikTok	Auto captions in the editor	Creators can preview and edit them line by line (TikTok Support)
Facebook and Instagram ads	An SRT file, or captions generated in Ads Manager	Name the file like ice_cream_ad.en_US.srt, or it will not upload (Meta)
LinkedIn ads	An SRT file	Strongly recommended, because videos autoplay without sound (LinkedIn Help)
X ads	Closed captions or text overlays	Strongly recommended (X Business)

Bottom line: SRT is the one caption file that YouTube, Meta’s Ads Manager and LinkedIn all accept, so write it once from the final script.

How do Voom’s captions work?

Voom’s captions are optional and burned into the picture: the spoken words appear on screen, timed to the voice word by word and styled to match the film’s design. Every shot keeps its content clear of the caption band at the bottom, so the captions do not cover the film’s own text or screens.

Because they are part of the picture, Voom’s captions show on every platform and player, including ones that ignore caption files. They also carry the trade-off of any burned-in caption: viewers cannot switch them off, restyle them or have the player translate them.

• Spoken words only. The captions show what the voice says, so a film with no voice-over has nothing to caption and its on-screen text carries the message. If a sound effect carries meaning, say it in the voice-over.
• One language per film. Captions follow the voice-over’s language, so a second language means a second film. Every voice speaks every language Voom offers, and Make a variation copies the request into a new draft.
• One MP4. The film arrives with its captions in the picture. If a platform or a policy needs a caption file, make the film with captions off and write the file from the script.

How do you check captions before you publish?

Check captions the way viewers meet them: on a phone, on mute and in the app’s preview. Five checks catch most problems, from a misspelt product name to captions hidden under the app’s buttons, and they work for burned-in captions, caption files and automatic captions alike.

1. Read them against the script. Every word, name and number should match what the voice says; automatic captions need this most.
2. Watch on a phone with the sound off. The story should still make sense, and each caption should stay up long enough to read.
3. Check the layout. Keep to one or two lines per caption, generally under 32 characters a line.
4. Preview the post in the app. Make sure its buttons, name and post text do not cover the captions, and turn off its automatic captions if yours are burned in.
5. Listen for sounds that matter. Caption any sound that carries meaning, or say it in the voice-over.

Repeat the checks for every size: on Voom each size is its own film, so turn captions on for each one. The guide to social media video sizes lists each platform’s safe zones, and how long a product video should be shows how many words a viewer will read at each length. To make a vertical ad with captions styled to match it, start with social media video ads.

Common mistakes with video captions

Most caption mistakes are invisible with the sound on, which is why they survive review. The common ones are unedited automatic captions, captions hidden under the app’s interface, two sets of captions at once, a file that will not upload and captions on only one version of a video.

• Publishing automatic captions unread. YouTube warns that they can misrepresent speech through mispronunciations, accents, dialects or background noise. Fix: correct them line by line.
• Captions under the app’s buttons. Fix: preview the post in the app before it goes live.
• Two sets of captions. Burned-in captions plus the platform’s own show every word twice. Fix: use one kind.
• A caption file that will not upload. Meta needs the language and country code in the file name. Fix: name it like filename.en_US.srt.
• Captions on one version only. Fix: turn them on for every size and language you publish.

When are Voom’s captions the wrong choice?

Voom’s burned-in captions are the wrong choice when viewers or a policy need control: a caption file for a course platform or a broadcaster, captions viewers can switch off or enlarge, several languages on one upload, or captions that describe music and sound. In those cases, make the film with captions off and add closed captions.

Burned-in captions remain the simpler choice for short feed videos and ads, because they need no file and no setting to show. For everything else a motion graphics film needs, from size to voice, see the guide to AI motion graphics.