A 9:16 crop keeps 31.6% of the picture.

Delivering one film in several shapes is not the same film several times. Each shape is a different rectangle cut out of the same frame, and how much survives is one division — min(a, b) / max(a, b) over the two aspect ratios. 16:9 into 1:1 keeps 56.3%. Into 4:5, 45%. Into 9:16, 31.6% — and the 68% that goes was framed months earlier by somebody who was not thinking about the vertical cut, because at the time there was not going to be one.

The engine is free and needs no account. Paste the frame and the shapes and every fraction comes back, with the axis each one takes — a delivery wider than the master crops the height, and every horizontal instinct is wrong for it. Give it the positions of what has to survive and it gives back the interval of crop positions that contain each one, which is sometimes empty: a subject wider than the window has no reframe at all, and two people further apart than the window is wide cannot share a crop, which is a decision about the cut rather than the export. And it computes the punch-in budget in pixels, because the geometry does not change with resolution and the pixels do — a 9:16 cut of a 4K master leaves 1215px for a 1080 delivery, and of an HD master leaves 608, which is a 1.78× upscale nothing in the export reports. Every lane ships a worked example that costs nothing. Writing the report needs credits.