US One-Sheet

Trim: 27 × 40 in (686 × 1016 mm)
Ratio: 27:40
Orientation: portrait
Bleed: 0.125 in (convention)
Safe area: 0.5 in inside trim (convention)
Colour: CMYK for press; many theatres light-box double-sided (reverse-printed back).
Billing block: Yes — bottom band, inside the safe area

The standard US theatrical poster since the mid-1980s; older sheets ran 27 × 41 in.
Billing block sits in the bottom band, usually set to the full live width inside the safe area.
Double-sided light-box sheets carry a mirrored, lighter back print — ask the printer whether they need a separate back file.

Source: Industry standard trim size.