The flexible ad format is a way of building a Meta ad where you upload several images and videos to a single ad, and Meta chooses which media and which format to show each person in each placement. One person might see a single image in their Instagram feed while another sees a short carousel in Facebook Feed, both from the same ad.
How the flexible ad format works
When you create an ad and choose the flexible format, you add a set of media, at the time of writing up to ten images and videos, along with several versions of your primary text and headline. Meta then assembles the ad at delivery time. Depending on its prediction of what will work best for that person and that placement, it may show one image, one video, or a carousel made from several of your assets.
This differs from dynamic creative, an older option that worked at the ad set level and mixed combinations of media and text. Meta has been folding several creative options, including flexible format, into its Advantage+ creative settings, and the exact names and limits change, so check Ads Manager for the current set-up.
Reporting sits mainly at the ad level. You can see which assets were used most, but the precise performance of each image in each format is less clear than when each ad is built separately.
Why it matters
Meta’s delivery system works best with a range of creative it can match to different people. For a small UK business that cannot produce a separate ad for every placement, the flexible format is a practical way to give the system that range from one upload. A café, a holiday let or a clothing brand with ten good photos and a couple of short clips can put them all into one ad and let delivery sort them.
The trade-off is control and learning. If you need to know exactly which message or image works, for example to brief a photographer or decide what goes on your website, a structured creative testing framework with separate ads gives clearer answers.
It also helps with placement fit. A vertical video can go to Reels and Stories while a square photo goes to feeds, without you building separate ads for each, provided you uploaded both shapes in the first place.
Common mistakes
- Uploading ten near-identical images, which gives the system nothing different to work with.
- Mixing assets for different offers or audiences in one ad, so the messages clash in a carousel.
- Assuming the most-shown asset is the best one, when delivery reflects what Meta predicted rather than a fair test.
- Using only landscape images, which leaves Stories and Reels with poorly fitted media.
- Expecting precise per-asset results to brief new creative.
How to act on it
Use the flexible format when you have a pool of genuinely different, on-brand media for the same offer: different angles, settings, people and lengths of video, in both square and vertical sizes. Write two to four versions of the primary text that each open differently.
Keep one offer per ad. Review the asset breakdown after a fortnight, remove media that never gets delivery, and add new material so the pool does not tire. When you need a clear answer about a specific idea, test it in its own ad. I use this approach to build creative diversity within Advantage+ campaigns without asking a client for dozens of separate ads.