CampaignReel

Ad placement specs against what generators output

Each platform asks for a different shape

TikTok states 9:16, 16:9 and 1:1 with minimum dimensions for each. YouTube's Masthead is widescreen or 16:9. Nine of the 15 tools in this register publish their aspect ratios on a page a buyer can read, and six publish nothing about shape. As of 2026-09-19.

Shape, as asked for by platforms and as published by toolsOne platform states three shapes with minimum dimensions for each; another states widescreen for its masthead placement. Of the tools in this register, one publishes its aspect ratios on a page a buyer reads and the rest do not. Square is accepted by a platform and published by no tool.What platforms ask forWhat tools publishVerticalStated, with minimum dimensionsPublished by one toolWidescreenStated for the masthead placementPublished by one toolSquareAccepted by one platformPublished by noneA vertical default against a widescreen placement is a deliberate change, not a crop
Fig. 1 Shape is the one spec that cannot be fixed after the fact, and it is the spec that the fewest tools publish.
What each side of the match publishes about the shape of the frame. Recorded 2026-09-19.
ItemWhat is publishedDetail
TikTok9:16, 16:9, 1:1With a pixel floor under each
YouTube MastheadWidescreen or 16:9Stated by the platform
Tools publishing a shapeNine of fifteenFrom two values to eight
Tools publishing nothingSix of fifteenResolution published, shape not

Inclusion rule. Platform requirements from the platform's own help page; tool shapes from the vendor's own page. The two are never mixed inside one cell. Order. Platforms first, then the tool side.

1Shape is the spec that cannot be fixed afterwards

Resolution survives a re-encode. Shape does not: cropping a vertical frame to widescreen moves faces out of it, and generated footage has no headroom because nothing was composed for a crop that was not planned.

So shape has to be right at generation time, which makes it the spec most worth knowing before a single second is generated and the one least often printed next to a price.

A courier in a red jacket stepping off an electric scooter outside a glass office building, framed vertically with the figure filling the height of the frame.The same courier and scooter outside the same building, framed square with the figure centred and equal space either side.The same courier and scooter outside the same building, framed widescreen with the length of the building running across the frame.
Fig. 2 One idea staged three ways. What is in the frame changes with the shape, which is why a vertical default and a widescreen placement need a deliberate decision rather than a crop.Three separate generations made for this page on 2026-09-16, not one image cropped three ways. Not output from any tool on the register.

2A widescreen default and a vertical placement need a deliberate change

Four rows here publish a default as well as a list: SceneMixer and Grok Imagine default to widescreen, Wan 3.0 defaults to adaptive, and MiniMax states that for text-to-video the ratio is required and cannot be left adaptive at all. A campaign aiming at a vertical placement therefore has to change a setting on two of those, supply a correctly shaped reference on the third, and pass a value explicitly on the fourth.

For the six tools that publish no shape the register cannot say what the default is, so the same campaign starts with an unanswered question and finds the answer in the footage.

3Square is accepted by one platform and published by five tools

One platform accepts 1:1 with a pixel floor under it. Five rows here name 1:1 among their ratios: Grok Imagine, Hedra, MiniMax, PixVerse and Wan 3.0, with Runway giving the equivalent as a 960:960 pixel pair.

The rest are recorded as not stated rather than unsupported. Several of them very likely produce square output; they do not say so on the page this register reads, and a placement that accepts three shapes is not the place to find out by generating.

  • Aspect ratios with minimum pixel dimensions
    Vertical 9:16 at 540x960 or more, horizontal 16:9 at 960x540 or more, square 1:1 at 640x640 or morenon-Spark adsTikTok Ads Manager, video ad specifications / recorded 2026-09-12
  • Masthead
    Widescreen or 16:9, autoplaying without sound for up to 30 seconds on desktopreservation onlyGoogle Ads Help, video ad formats / recorded 2026-09-12
  • Aspect ratios
    16:9 by default, with 9:16 availablestated on the sitescenemixer.com / recorded 2026-09-19

4Sources

Format requirements come from Google Ads Help, read 2026-09-12, and tool limits from each vendor page listed on published limits, read 2026-09-19. The rule against mixing the two is on method. Nearby: File limits, Ten seconds, Shape first.