YouTube Shorts ads: 10-30 second vertical cuts from a longer clip

Google Ads Help recommends vertical 9:16 video for Shorts ads, says video ads can be up to 3 minutes while only the first 60 seconds play in the Shorts feed, and suggests 10 to 30 second vertical videos for action-oriented ads. With Sume, one video trim at $0.02 turns a longer clip into that size.

These points come from the Google Ads Shorts ads page (read 2026-10-10). I added only the Sume mechanics.

What Google's page recommends

The page recommends vertical video assets at 9:16 and notes that horizontal and square static image assets can be used but are less optimal. It says video ads can be up to 3 minutes, though only the first 60 seconds play on the Shorts feed, and advises adding videos under 60 seconds. It recommends sound, music, voice-over or both, because it increases conversions; organic and social-first content; action-oriented ads using 10 to 30 second vertical videos; and authentic creator assets when you can. Videos must be uploaded to YouTube, public or unlisted.

Cutting the clip

Video trim keeps the source unchanged and returns a new MP4. Send start plus one of end or duration, and set duration between 10 and 30 for an action-oriented ad. The audio field defaults to keep, so the voice-over or music stays. Exact precision is the default and cuts frame-accurately, and the result gives duration_seconds and actual_start_seconds so you can see exactly what you got.

If you want to join a hook and a demo, use Timeline 1.0 instead. Each slot has a start, a duration, an optional source_in, and a fit mode; set the audio duration_seconds to the total length you want, 30 for instance.

Picking the 30 seconds

The page says only the first 60 seconds play, but the trim is about attention, not allowance. Put the hook within the first seconds, show the product or result by the middle, and end on the call to action. If the source is a 90-second explainer, cutting the best 20 seconds is usually a better ad than cutting the first 60.

You can use the unbilled Timeline plan to confirm total length and segment count when you combine clips, and you can use the video inspect call to pull stills for a quick look at what a cut contains; inspect's probe-only call is free.

Where Sume stops

The page's recommendation to use authentic creator assets is advice about content, which Sume cannot supply. Likewise hosting happens on YouTube: the ad must be uploaded there as public or unlisted. And if the cut includes generated footage, check the disclosure rules for the platform before you run the ad.

Cost is small enough to test several cuts. A trim is $0.02 a job under the Video trim docs, so cutting 10, 20 and 30 second versions of the same source is six cents in trims, and each can be uploaded as its own ad for comparison. Timeline renders are priced by output minute, $0.10 per minute rounded up, so a 30-second assembled ad is $0.10.

Remember the page also says Shorts ads show on mobile, desktop, tablet and connected TV, but that Shorts is a mobile-optimised experience. A vertical file is the right default, and the first seconds should work with the sound off as well as on, since many viewers will not turn it on.