Start with the seat, not the screen
Every good theatre room is planned backwards from where people will sit. Fix the primary seating position first, then derive the screen size, then the speaker positions, then the acoustics, and only then the joinery. Doing it the other way round — choosing a 120-inch screen because the wall is wide — produces a room where the front row has to move their eyes across the image to follow it.
| Seating distance | Recommended screen diagonal | Field of view | Suits |
|---|---|---|---|
| 2.4 m (8 ft) | 75–90 in | ~36° | A converted bedroom, 4K flat panel |
| 3.0 m (10 ft) | 95–110 in | ~38° | The most common Mumbai theatre room |
| 3.6 m (12 ft) | 110–130 in | ~40° | A dedicated 180–220 sq ft room |
| 4.2 m (14 ft) | 130–150 in | ~40° | Two rows with a riser |
| 5.0 m (16 ft 6 in) | 150–165 in | ~40° | Villa or penthouse theatre |
THX recommends roughly a 36–40° horizontal field of view. Going wider looks impressive for ten minutes and becomes tiring.
Room geometry and the numbers that matter
A rectangle is better than a square, and a room whose length, width and height share simple whole-number ratios is worse than one that does not — square and 2:1 rooms concentrate standing waves at particular frequencies, which is why a 12 ft x 12 ft theatre booms at one note however good the subwoofer is. Where the room is fixed, the fix is absorption and speaker placement rather than regret.
- Minimum usable room: about 120 sq ft with a 2.75 m ceiling. Below that, a good living-room setup will beat a cramped dedicated room.
- First row off the front wall: 1.2 m minimum, 1.5 m better. Sitting closer puts you inside the screen's near field and inside the front speakers' dispersion.
- Back row off the rear wall: 600 mm minimum. Heads against a hard rear wall get a comb-filtered mess of reflections.
- Riser for row two: 300 mm high, 1.5 m deep. Below 250 mm the back row watches the front row's heads.
- Seat width: 750 mm for standard recliners, 850 mm for wide. Allow 900 mm clear behind a fully reclined seat.
- Ceiling: 2.75 m finished is comfortable. If you are dropping a ceiling for services, you need 3.05 m to start with.
Design and build under one accountable roof
Acoustics: the four surfaces that decide the room
Acoustic treatment is where a modest system starts sounding expensive. The priority order is fixed and it is not the one most people guess: first reflection points on the side walls, then the front wall behind the screen, then the ceiling reflection point, then the rear wall, and finally bass trapping in the corners. Treating the side walls alone typically gets you two-thirds of the audible improvement.
| Surface | Treatment | Material | 2026 rate, ex-GST |
|---|---|---|---|
| Side walls, first reflection | 50 mm absorber panel, fabric-wrapped | Rockwool 48 kg/m³ + acoustic fabric | ₹340–₹620 / sq ft |
| Front wall behind screen | Full absorption | 50 mm rockwool, black fabric | ₹290–₹480 / sq ft |
| Ceiling reflection zone | Absorptive cloud or stretch ceiling | Barrisol or fabric-wrapped frame | ₹480–₹1,150 / sq ft |
| Rear wall | Diffusion, not absorption | Timber QRD diffuser or slat panel | ₹620–₹1,400 / sq ft |
| Corners | Bass traps | Triangular 100 mm rockwool, floor to ceiling | ₹4,800–₹9,500 each |
| Floor | Carpet over underlay | Broadloom, 8 mm felt underlay | ₹165–₹420 / sq ft |
| Door | Acoustic seal set + solid core | Perimeter seals and drop-down bottom seal | ₹9,500–₹22,000 per door |
The air-conditioner problem
This is the single most common failure in Indian home theatres and the hardest to fix afterwards. A wall-mounted split unit runs at 38–44 dB(A) at the indoor unit. A quiet film scene sits around 30–35 dB. So the AC is not background noise — it is the loudest thing in the room during dialogue. The answer is a ducted or cassette unit with the fan coil outside the room, lined supply ducting, and low-velocity linear diffusers.
| Option | Noise at seat | Extra cost over a split | Verdict |
|---|---|---|---|
| Wall-mounted split, 1.5 TR | 38–44 dB(A) | — | Audible in every quiet scene |
| Cassette in a false ceiling | 34–38 dB(A) | ₹22,000–₹40,000 | Better; still audible |
| Ducted split, unit outside the room, lined duct | 26–30 dB(A) | ₹55,000–₹1,10,000 | What we specify |
| Ducted with an acoustic plenum box | 22–26 dB(A) | ₹95,000–₹1,80,000 | For rooms above ₹15 L |
Also plan for return air. A sealed theatre with supply only goes positive-pressure and the door becomes hard to open.
Lighting, sightlines and the things people forget
- Bias lighting behind the screenA 6500 K strip at about 10% of screen brightness reduces eye fatigue and makes blacks look deeper. ₹3,500–₹8,000.
- Step lighting on the riserRecessed 1 W markers, separately dimmed. Someone will walk in during the film.
- No downlights in the ceiling reflection zonePut them behind the seating line. A downlight above the first row bounces off a glossy screen.
- One dimmable scene controllerThree scenes: entry, viewing, clean-up. A wall of individual switches never gets used properly.
- Blackout before anything elseA 2.4 m x 1.5 m window undoes ₹4 L of acoustic work. Blackout blinds in a side channel, ₹550–₹1,400 per sq ft.
- Cable routing at first fixHDMI 2.1 in a 32 mm conduit with a draw string, speaker cable in separate conduit, and a spare. Retrofitting one HDMI run costs ₹18,000 and a week.
Clients arrive asking which projector. They leave having spent the money on the room, and it is the right decision every time.
Greenbox principal designer
What a home theatre costs in 2026
| Level | Room size | Scope | Cost, ex-GST |
|---|---|---|---|
| Entry | 120–150 sq ft | Side-wall absorption, carpet, blackout, ducted AC, basic joinery, seating for 4 | ₹6,50,000–₹10,00,000 |
| Mid | 160–200 sq ft | Full treatment, riser, stretch ceiling, acoustic door, scene lighting, 6 recliners | ₹11,00,000–₹18,00,000 |
| High | 220–320 sq ft | Diffusers, plenum HVAC, veneer and fabric joinery, two rows, bar counter | ₹19,00,000–₹28,00,000 |
Excludes projector, screen, AVR, speakers and subwoofers — budget a further ₹4 L–₹40 L on AV depending on the system.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What is the minimum room size for a home theatre?+
About 120 sq ft with a 2.75 m finished ceiling — roughly 12 ft by 10 ft. Below that you cannot get 1.2 m in front of the first row and 600 mm behind the back row while keeping the seats out of the side speakers' near field. In a smaller room, a well-set-up living-room system will sound better than a cramped dedicated one.
How far should you sit from a 120-inch screen?+
A 120-inch 16:9 screen is 2.66 m wide, so the primary seat wants to be 3.4 to 4.2 m away — about 11 to 14 feet. That puts the horizontal field of view in the 36 to 40 degree band. Closer than 3.2 m and you start moving your eyes across the image rather than taking it in.
Do I need acoustic treatment or will good speakers be enough?+
Treatment first. An untreated 150 sq ft room with hard walls has a reverberation time around 0.7 to 0.9 seconds, which smears dialogue regardless of what is playing it. Treating the side-wall first reflection points and the front wall — usually ₹90,000 to ₹1,60,000 of work — does more for intelligibility than doubling the speaker budget.
Which air-conditioner is best for a home theatre?+
A ducted split with the fan coil unit sited outside the room, lined supply ducting and low-velocity linear diffusers, targeting 26 to 30 dB(A) at the seat. It costs ₹55,000 to ₹1,10,000 more than a wall split, and a wall split at 38 to 44 dB(A) is louder than quiet dialogue, so the upgrade is not optional in a serious room.
Can a living room work as a home theatre?+
Yes, and for many families it is the better decision. You lose light control and you cannot treat the side walls properly, so you plan around it: a flat panel rather than a projector, a soundbar-plus-subwoofer or a compact 5.1 layout, heavy curtains, and a rug on hard flooring. See our home theatre project page for one we did this way.