Amazon Sponsored Brands video specs, the rules that reject a file, and the 16:9 trap

You have a vertical ad that works. It ran on Meta, it ran on TikTok, the retail team wants one on the Amazon listing by Friday, and the fastest thing anyone can think of is a crop. Amazon accepts one aspect ratio, prints it in four words, and separately refuses the standard way of forcing a file into it. Everything below was read off Amazon's own pages on September 3, 2026. I quoted rather than summarized, because a spec that has been through three blog posts stops being a spec.

01What are the Amazon Sponsored Brands video specs?

Fourteen fields, and Amazon publishes every one. Frame: 1280x720, 1920x1080 or 3840x2160px, 16:9 square pixel only, progressive scan, Main or Baseline profile. Motion: 6 to 45 seconds, H.264 or H.265, minimum 1 Mbps. Sound: PCM, AAC or MP3, stereo or mono, minimum 96 kbps at 44.1khz. Container: .MP4 or .MOV, 500MB or less.

Three of those fields carry the weight. "16:9 (square pixel) only" removes an entire vertical library in one line. The 500MB ceiling decides how long a 4K cut can be. And Main or Baseline is the field nobody reads, because it sits between two numbers and looks like housekeeping until an export written at High profile comes back with no explanation attached.

02How long should an Amazon Sponsored Brands video be?

Twenty seconds or less, and that is Amazon's recommendation rather than mine. The field reads "Between 6 and 45 seconds (20 secs or less highly recommended)." The range is the filter and the parenthesis is the advice. A 45-second cut will upload cleanly. It will also be the longest thing on a page a customer arrived at to buy one specific object.

Amazon publishes two pieces of creative guidance for video, with no test behind either. "Show the product in the first two seconds of the video to make the best first impression." And "End with your logo," because "Customers are more likely to remember your brand when the logo is the last thing they see." I follow both. I went looking for a platform study with a stated sample behind that advice and found nothing, so a lift figure quoted at you for a demo format traces back to a case study with one advertiser in it. The craft of filling the twenty seconds sits on the sister journal, in how a short ad is built second by second.

Every other placement lets you letterbox your way out of a bad crop. Amazon writes letterboxing down as a reason to reject the file.

Amazon's moderation guide, read September 3, 2026

03The rules that reject a file that meets every number

An export can clear all fourteen fields and still come back. Amazon's moderation guidance for Sponsored Brands and display ads carries the reasons, and two of them catch the export rather than the idea. Videos "must not have black bars on any side, which means letterbox and pillar-box formats are not permitted." And "Black or blank frames at the start or end of videos" sits on the list of common rejection reasons. A fade from black lands there.

The lower right corner rule is the one I have never seen in a downloadable template. Amazon gives no reason and you do not need one: moving an end card costs a minute, and a rejected file costs a delivery slot. Substantiation is the other quiet row. It reaches further than a video person expects, because a claim in an end card decides a category question before Amazon ever sees the file, and for a cosmetic that line is drawn in which claims turn a skincare product into a drug.

04A 9:16 cut does not become a 16:9 ad by cropping

A frame is composed for its shape. Vertical work puts the subject on a tall path for the eye and uses the height on purpose, so a 16:9 window cut out of it takes either the top or the bottom, and in our own reels that is usually a face, a pair of hands, or the product. The crop is the cheapest operation on the timeline and the most expensive one on the page.

The fix costs nothing at the direction stage and a re-shoot afterward. Where a brand sells on Amazon, the 16:9 version is a named deliverable on the board, framed for its own shape, before anything renders. That is what native sizes has to mean on a monthly plan, and what a creative retainer includes sets out the rest of that line. Type is the other half. A caption laid out for a tall frame lands somewhere else in a wide one, so the legibility floors we measure against hold in both, and safe zones as a constraint rather than a guideline is why the layout gets decided before anyone draws it.

05Does Sponsored Display video use the same spec?

No, and Amazon's public ad-specs index has no Sponsored Display video entry to check. What exists is a guide called Get started with display ads with video, and it carries a different set of numbers for what looks like the same job. I read both pages on the same day. One export does not clear both.

Three rows there repay a second look. The audio floor is 96 kbps on one page and 92 kbps on the other, four kilobits apart for a reason neither page gives. The frame rate lists disagree. And the display guide asks for 1920x1080 or higher, so the 1280x720 file Sponsored Brands accepts sits below the floor next door. One master at 1920x1080, 16:9, twenty seconds, 29.97fps, 4 Mbps video and 128 kbps AAC at 48kHz clears every column above. That set of values is mine, derived from the two published tables rather than printed by Amazon.

AMAZON MASTER - one file, both placements

  Ratio           16:9, square pixel
  Resolution      1920 x 1080
  Duration        0:20 or under   (floor 0:06, ceiling 0:45)
  Container       .MP4
  Video codec     H.264, Main profile, progressive
  Video bitrate   4 Mbps
  Frame rate      29.97 fps
  Audio codec     AAC, stereo
  Audio bitrate   128 kbps
  Sample rate     48 kHz
  File size       under 500 MB

CHECK ON THE FILE, NOT THE TIMELINE

  [ ] no black bars on any side, top or bottom
  [ ] first frame carries picture, last frame carries picture
  [ ] lower right corner clear of text and logo
  [ ] nothing flashing, blinking or pulsating
  [ ] no upscaled or stretched source in any shot
  [ ] on-screen text and mix in the site's primary language
  [ ] every claim on screen has substantiation on file

Signed off by: ______________   Date: __________

Every other placement makes you argue about taste. This one publishes its entire test in fourteen fields and two rejection rules, and files still come back, because the crop happened on the last afternoon and nobody opened the page.