YouTube Shorts Ad Specs: Format, Safe Zones, Hooks

Ads running in YouTube Shorts should be vertical 9:16 video at 1080x1920 or better, with titles, captions, and product shots kept inside the safe zone — clear of the bottom of the frame where the channel name, description, and CTA appear, and clear of the right edge where the engagement buttons stack. Duration limits and encoding requirements are set by Google Ads and can change, so confirm them there at upload. The parts that don't change: go native vertical, respect the overlays, and open with the hook.

What aspect ratio do Shorts ads need?

9:16. Shorts is a full-screen vertical feed, and Google will surface vertical creative there; horizontal 16:9 assets either don't fit the placement or show up with heavy letterboxing that marks them as recycled TV-style ads. If your existing assets are horizontal, re-frame for vertical rather than cropping — subjects framed for widescreen usually lose their composition in a straight crop.

Where is the Shorts safe zone?

The Shorts player draws UI over your video: channel info, the ad's headline and CTA along the bottom, and the like/dislike/comment/share column on the right. Treat the bottom quarter and the right rail as no-go zones for anything the viewer must read. Center your burned-in captions vertically in the middle band and keep the product hero shot in the center of frame.

How long should a Shorts ad be?

Short. Shorts viewers are in a rapid swipe rhythm, and the format rewards ads that state their case fast. More important than total runtime is where the payoff sits: front-load the hook rather than saving the reveal for the end, because most viewers never reach the end. Measure your openings with hook rate, and generate alternative first lines with a hook generator so you're testing hooks, not guessing.

Does sound matter on Shorts?

Shorts leans sound-on like TikTok, so voiceover and music carry real weight — but muted viewing still happens, especially outside the home. Burned-in captions keep the ad intelligible either way and give sound-off viewers a reason not to swipe.

Once the specs are right, what decides performance?

Creative, tested at volume. The same product with ten different hooks will produce a spread of outcomes, and the winner is rarely the one you'd have picked — which is why ROAS is discovered by testing, not predicted. Polaris is built for exactly this: connect it to Claude over MCP and generate batches of vertical UGC-style ads inside the chat — attach a product photo, pick options from tappable cards, and download the batch as a ZIP. It's a fast way to feed a Shorts test with AI UGC ads (first 12 free, no card), then judge the results against your margins with a ROAS calculator.