Video for social media: formats, lengths and captions that work

Short video for NGO social media is not a trailer cut down from a longer film. People meet it on a phone, in a feed, often in a few spare seconds and often in a noisy place. The first frame, the first line of text and the first spoken words decide whether anyone stays.

That means the format, the length and the captions are editorial decisions, not technical settings to fix at the end. Plan them before the shoot, because the way you frame a scene and the way someone speaks to camera will shape every version you can later publish.

Reels, Shorts and TikTok are built for viewing on a phone held upright, so vertical video should be your starting point. YouTube treats a video as a Short when it has a square or vertical aspect ratio and is up to three minutes long.¹

In practice, we frame faces and key actions near the centre of the shot. This leaves room for captions, platform buttons and the account name, and it lets an editor crop a square or horizontal version without losing what matters. LinkedIn also accepts video in more than one shape, so check its help centre for current specifications before you export.

• Vertical: Instagram Reels, YouTube Shorts, TikTok, stories
• Square: a safe compromise for feeds where people scroll past
• Horizontal: websites, YouTube long-form, presentations and events

Maximum lengths have grown on every platform, but a longer limit does not mean longer is better. Instagram says you can record and edit reels of up to 20 minutes, but notes that reels over three minutes will not be recommended to new audiences.² YouTube allows Shorts of up to three minutes.¹

TikTok and LinkedIn also change their limits from time to time and sometimes vary them by account or posting method. Treat any figure as something to check on the day you publish. For most advocacy and programme stories, a single clear idea told in under a minute is easier to finish and easier to watch to the end.

Many people watch social video in silence. In 2021 LinkedIn reported that 79 per cent of videos in its feed were watched with the sound off, and that displaying captions in the same language as the audio can help drive more social actions.³

So write the video to work without sound. Open with a strong image and a short line of on-screen text that says what the story is about. Keep text large, high in contrast and on screen long enough to read twice. If the story depends on a speaker, burn in captions or upload a caption file so viewers do not have to guess.

Captions are not only a reach tactic. W3C describes them as a text version of the speech and non-speech audio needed to understand the content, provided for people who are Deaf and others who cannot hear the audio.⁴ Closed captions can be shown or hidden by viewers, while open captions are always displayed.⁴

Platforms now offer automatic captions; TikTok, for example, lists auto-generated captions among its accessibility tools.⁵ They are a useful starting point, but W3C warns that automatic captions do not meet user needs or accessibility requirements unless they are confirmed to be fully accurate.⁴ Check names, places, figures and words in Kinyarwanda, French or Kiswahili with particular care.

Captions help people who cannot hear. Description helps people who are blind or cannot see the video well. W3C notes that, for some videos, speakers can integrate the visual information as the video is planned and recorded, so that separate description is not needed.⁶

For short social video this is usually simple. If a key fact appears only as on-screen text or a chart, have someone say it as well. W3C advises that when writing the script you make sure all relevant visual information is included.⁶ Add alt text or a clear post description where the platform allows it.⁵

Good reels production starts with one well-planned shoot that serves several outputs. Agree the single message first, then list the vertical, square and horizontal cuts you need, and which platform each one is for. Record clean audio, because accurate captions depend on it.

Make consent forms cover every platform and format you intend to use, including short clips taken from a longer film. Keep a simple log of versions, caption files and publication dates. In our own practice, we review each cut on a phone, with the sound off, before anything is published.

• One clear message agreed before filming
• Faces and key action framed near the centre
• Vertical, square and horizontal cuts listed in advance
• Current platform limits checked on the day of publishing
• First frame and opening text work without sound
• Captions reviewed line by line, especially names and figures
• Key visual information also spoken aloud
• Consent covers every platform and cut