Neither length wins universally. 30-second brand videos perform better for cold prospecting and feed placements, where completion rate and click-through favor short runtimes; 60-second videos perform better for considered purchases and CTV/OTT, where narrative depth drives recall. At AI production costs of roughly $67–$530 per video, the strongest play is producing both and scaling the ROAS winner.
Choose by funnel stage and placement, not by a universal winner: run 30 seconds for top-of-funnel social feeds and prospecting audiences, and reserve 60 seconds for brand storytelling around high-consideration or high-ticket products and for CTV/OTT placements — connected-TV analyses similarly find a mid-length sweet spot rather than a blanket win for the longest cut.
The hook decides more than the runtime. Documented performance-ad production identifies a 1.5-second window for a scroll-stopping hook, and the first 3 seconds as the portion that determines a short ad's performance — so a 60-second video that opens slowly loses to a 30-second one with a strong first beat, regardless of format. Whatever length you pick, concentrate the majority of iteration time on the opening seconds.
Let the creative beats set the length — don't compress or pad to hit a number. In one documented production, the invideo agent pushed back on a request to compress a script to 15 seconds and recommended 20 seconds to preserve the hook beats and give the promo time to register — the length was earned by the beats, not imposed. Documented AI productions scale runtime with format ambition: around 15 seconds for a UGC try-on ad, 20 seconds for a cinematic editorial film, and 30–40 seconds for full brand films. If your script's beats genuinely fill 60 seconds, cutting to 30 will cost the story; if they fill 30, stretching to 60 adds dead air that kills completion.
Test both lengths instead of predicting the winner. invideo is an agentic video creation tool with all the current video models available, which makes producing a 30-second and a 60-second cut of the same concept cheaper than one traditional shoot: documented productions ran ~$67 for a 30–35-second B-roll package, ~$75 per UGC ad, ~$530 for a 30-second multi-character montage, and $425–$1,300 for 30–40-second brand films. One production note is worth knowing for longer cuts: models like Seedance 2.0 cap each generation at roughly 15 seconds, so the invideo agent decomposes a 60-second video into segments and stitches them — a 40-second reference ad in one documented workflow required four generation passes. Ship both lengths, read completion and ROAS in your ads manager, and scale the winner — as one documented workflow puts it, you can ship all versions in parallel and scale the one that actually performs, instead of betting on a single pre-selected length.
Watch some of these to see what works for you:
any other agent or any other tool out there would have just compressed my script to 15 seconds and it would probably happen at the cost of quality. But as you can see agent one pushes back because it understands what task rabbit's other ads look like and it's strongly recommending staying at 20 seconds to land the quality that we want.
— invideo's creative team