One master cannot satisfy five platforms.

TikTok leaves 59.9% of the frame clear of its own interface. Reels leaves 60.5%, Shorts 68.8%, the Instagram feed 59.5%, LinkedIn 24.2%. Every one of those lines looks workable. The region clear on all five at once is 21.8% — because a safe area across a set is an intersection, not a list, and an inset on the right from one platform compounds with an inset on the bottom from another into a rectangle neither spec sheet mentions.

The engine is free and needs no account. Paste the delivery — one master frame, the length and weight of the cut, the size of its smallest type, and every platform it has to reach. The aspects do not intersect either: a 9:16 master centre-cropped to 4:5 keeps 70.3% and to 16:9 keeps 31.6%, so what survives every target at once is the intersection of the crops. The ceilings are a minimum, not a list — and because size = bitrate × duration ÷ 8, a 256 MB file cap on a 180-second cut is an 11.93 Mbps ceiling against the 20 Mbps the same platform publishes, so the number that actually binds appears in nobody’s documentation. And legibility scales with the delivered width: a thumbnail is judged at its 246 px mobile preview, not at 1280, so 48 px of master type is 10.9 px where the decision is made. Every lane ships a worked example that costs nothing. Writing the report needs credits.