9:16 vertical
TikTok, Instagram Reels, YouTube Shorts, Snapchat. Highest reach for short-form. Keep captions and key visuals in the safe central band.
1:1 square
Great for feed posts on Instagram, Facebook and LinkedIn. Works everywhere but not optimal anywhere.
16:9 widescreen
YouTube long-form, LinkedIn hero videos, embedded landing-page loops, and TV/DOOH campaigns.