The 5.5 × 8.5 in bi-fold
A 5.5 × 8.5 in bi-fold is a Letter sheet folded once — a cover and back at half-letter size, opening into one wide spread inside.
Closed size5.5 × 8.5 in
Opens to11 × 8.5 in
Panels4
FilesLayered PSD, smart objects
It's the default folded piece in US print, and mostly for practical reasons: it comes off standard 8.5 × 11 in stock with a single fold and no trimming, so every printer and copier in the country can make one. That's how it ended up carrying restaurant menus, event programs, church bulletins, real estate sheets, wedding and funeral programs — the everyday four-page piece that has to be produced quickly and cheaply.
The fold changes the shape more than people expect. Closed, the cover is proportionally taller and slimmer than the Letter sheet it came from, so a layout that sits comfortably on a full page feels narrower once it's folded down. Open, it flips to a wide landscape spread with the crease down the middle, which is the room to run an image or a headline across both panels; just keep faces and small type off the fold.
In the sets: closed on the cover and open flat, tented and shot from above, so you can present the half-letter cover and the full inside spread in one go. Each is a layered PSD with smart objects — the artwork sits on its own layer, so replacing it leaves the fold, lighting and shadow untouched.