— Cinema Sizer · Home cinema
Dedicated cinema, 8 m room, reference scope — 164" screen
Problem. A dedicated 8 m-long, 5.5 m-wide, 3.2 m-high room is being built as a film-first cinema, and the screen has to feel immersive from the back row rather than merely large from the front. The decision is which viewing-angle tier and aspect the geometry can actually carry before the side walls or throw distance become the limit.
Answer. At the reference THX-style ~36° rear-seat angle with a 2.39:1 scope screen, this room resolves to a 3.83 m-wide by 1.60 m-high image — about a 164" diagonal — seen from a 5.9 m rear seat, with room for four rows and an overhead-capable Atmos layout. The wall does not cap the image here, so reference geometry is delivering the largest defensible screen for the deepest seat.
02 / In depth
How this preset reads — the engineering view.
The tool sizes the screen from the horizontal angle it should subtend at the rear seat, not from a fixed room fraction: screenW = 2·tan(angle/2)·rear-seat-distance. Reference tier uses the THX-grade ~36° target, wider than the SMPTE ~30° premium and ~26° media angles, so for one identical room the reference tier always calls for the largest immersive image — provided the usable wall can hold it.
For this state the 5.9 m rear seat and 36° angle give 2·tan(18°)·5.9 ≈ 3.83 m of width, comfortably inside the ~4.5 m usable wall (5.5 m less a 0.5 m absorption budget each side), so the geometry — not the wall — sets the size. That 3.83 m width at 2.39:1 is a 1.60 m-high scope image, a ~164" diagonal, with an indicative 1.8× lens throw of 6.9 m inside the 8 m length. The seating depth yields four rows of five seats (20), and with 3.2 m of height and that seat count the format selector opens the full 9.1.6 overhead array (16 channels).
Vary the inputs and the direction is monotonic: a deeper rear seat (longer room) widens the screen until the wall caps it; a wider room lifts that cap; more height and more seats unlock richer overhead formats. Choosing 2.39:1 over 16:9 gives a wider, shorter scope image that suits a film-first room and avoids letterboxing bars on cinemascope content; dropping to the premium or media tier narrows the angle and shrinks the same-room screen.
The model is planning geometry: it does not model acoustics, screen gain or projector lumens, ambient-light rejection, sightline riser heights, HVAC or wiring routes, or the specific projector and lens that must hit the 6.9 m throw. Treat the 164" figure and 9.1.6 format as the envelope the room can carry, then confirm loudspeaker positions, riser sightlines and lens selection in CAD.
What this preset deliberately does not solve
- Screen size is pure viewing-angle geometry — no gain, lumens or ambient-light modelling.
- 9.1.6 is offered because height and seat count allow it, not confirmed against ceiling structure or wiring.
- The 6.9 m throw is an indicative 1.8× mid-band; the actual lens throw range must be checked per projector.
How this preset differs from its siblings
Its sibling, the media-room 16:9 preset, models a smaller 5×4×2.7 m multi-use room at the SMPTE ~30° premium angle and returns a ~92" 16:9 image with a floor-biased 5.1.4 layout. Use this reference-scope preset for a purpose-built, film-first cinema where room depth and height are generous and a large scope screen is the goal; use the media-room preset for a compact shared room where everyday 16:9 content and a shorter throw dominate.
03 / Hydrated calculator
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