Social media carousels: how to plan posts people actually swipe

A carousel is a single post made of several slides that people move through by swiping or tapping. It suits content that has an order: steps, a before and after, a short story or a set of findings. For communications teams it is one of the few feed formats that rewards explanation rather than a single striking image.

The format is not identical across platforms. On Instagram, you can upload up to 20 photos and videos and share them as a single post in Feed.¹ A LinkedIn carousel shared from a page or profile is usually a document post: an uploaded file that LinkedIn displays page by page. LinkedIn's developer documentation says documents can be PPT, PPTX, DOC, DOCX or PDF files of up to 100MB and 300 pages.² LinkedIn's paid Carousel Ads are a separate format, with 2 to 10 cards.³

Most weak carousels fail before anyone opens a design tool. They try to cover a whole annual report, a whole programme or a whole policy. Before you plan slides, write two sentences: the one thing you want people to understand, and the one thing you want them to do next. That action might be reading a report, registering for an event, sharing a service with someone who needs it or simply following the account.

If you cannot write those two sentences, the content is not ready to become a carousel. It may need to be a longer article, a short film or several separate posts. A narrow brief also makes approval easier, because reviewers can judge every slide against a clear purpose.

Write the carousel as a storyboard in a simple document before designing anything. Give each slide a number, a headline of a few words and, if needed, one supporting line. Read the headlines alone in order: they should tell the whole story without the supporting text. A structure that works for most carousel post ideas is the following.

Fewer slides are usually better than more. Aim for the smallest number that still tells the story completely. If a slide exists only to fill a template, remove it. Then share the storyboard with the people who will approve the post, so that questions about wording and facts are settled before any design time is spent.

• Slide 1, the hook: a specific question, a surprising finding or a clear promise of what the reader will learn.
• Slide 2, the context: why this matters now and who it affects.
• Middle slides, the substance: one step, fact or example per slide.
• Second to last slide, the proof: a verified figure, a short quotation used with consent, or a photograph.
• Last slide, the action: what to do next and where to find more.

Most people will see your carousel on a small screen while scrolling. Use one message per slide, large type and generous margins. Keep the same template, colours and headline position across the set so the slides feel like one piece. A small slide number or progress marker helps people see that there is more to come and how long it is.

Check the specification for the exact format before you export. LinkedIn's Carousel Ads specifications, for example, call for a 1:1 image ratio, recommend at least 1080 x 1080 pixels, accept JPG or PNG files up to 10 MB and limit card headlines to 45 characters.³ Platform specifications change, so confirm them in each official help centre at the start of every campaign rather than relying on an old template.

Text must stand out from its background. The WCAG contrast standard asks for a ratio of at least 4.5:1 for normal text and 3:1 for large text.⁴ Avoid placing text over busy photographs unless you add a solid panel behind it.

A carousel built from images of text is invisible to someone using a screen reader unless you describe it. Instagram lets you write your own alt text for a photo before you share it, through the advanced settings, and to change it after posting; otherwise it generates a description automatically using object recognition.⁵ Write your own for every slide that carries meaning.

When a slide is mostly words, the alt text should repeat those words. The W3C guidance on images of text states that the text alternative must contain the same text presented in the image.⁶ For photographs, describe what matters to the story: who is shown, what they are doing and where, in one or two sentences.

Repeat the key message and the call to action in the caption as well. People who do not swipe, and people using assistive technology, should still get the point. Write the caption in plain language and put the most important words first, because long captions are often shortened in the feed.

An Instagram carousel for NGOs or a LinkedIn carousel for a ministry or UN agency works best when it turns something complex into a clear sequence. Choose the platform by audience: LinkedIn for partners, donors and professionals, Instagram for wider and often younger publics. These formats tend to suit development and public sector communications:

• Five findings from a new report, one per slide, with a link to the full document.
• How to access a service: eligibility, steps, documents needed and where to go.
• A programme explained: the problem, the approach, the people involved and the results.
• Myth and fact pairs that correct common misunderstandings.
• A photo story following one person or place, with consent and dignity.
• Event highlights: the key decisions or commitments, not only photographs of the room.
• Behind the scenes: how a project, survey or campaign was actually done.

Before publishing, test the carousel on a phone, not only on a desktop monitor. Ask someone outside the project to swipe through it and tell you what it was about. Check every figure, name and caption against the original source, and confirm that everyone shown has given consent.

After publishing, look beyond likes. Saves, shares, comments and clicks to the linked resource tell you more about whether people found it useful. In our own practice, we keep a short note of which hooks and structures worked for each audience, and use it to brief the next carousel.

• One idea and one action, written down before design
• Headlines alone tell the story in order
• A first slide that gives a clear reason to swipe
• Current platform specs checked in the official help centre
• Large type with strong colour contrast
• Your own alt text on every meaningful slide
• Key message and link repeated in the caption
• Figures, names and consent checked before posting