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Projector or TV?
The answer depends on three things: how big the picture should be from your seat, how much light the room lets in, and when you watch.
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Why the size comes first
A picture feels like cinema when it fills about 36 to 40° of your view (the commonly cited THX figure; 30° is the widely quoted SMPTE minimum). From 3 metres that is roughly 88 to 99 inches; from 4 metres, 117 to 132 inches. TVs are widely sold up to 98–100 inches, so beyond that a projector is usually the practical way to get there. The screen size calculator does the sums for any distance.
Brightness, in plain numbers
Screen brightness (in nits, candela per square metre) = projector lumens × screen gain ÷ (π × screen area in m²). Cinema white is 48 nits (14 foot-lamberts, the DCI and SMPTE reference) in a dark auditorium. For a room with some light, about 40 fL (137 nits) is a common rule of thumb and the figure the calculator uses; published suggestions range from about 30 to 50 fL. Brightness figures on specification sheets are usually measured in the brightest, least accurate mode; calibrated output is often much lower, so leave headroom, especially for HDR.
Light is the deciding factor
- Dark room: a projector on a matte white screen gives the most cinema for the money at large sizes.
- Some light: an ambient-light-rejecting (ALR) screen keeps contrast when the curtains are not fully closed; most ALR screens are made for a particular projector position (ultra-short-throw from below, or a standard projector at the right height), so match them.
- Bright room or daytime viewing: a TV is far brighter and keeps its blacks; a projector looks washed out.