The room you see and the room you hear

Every home theater is born twice: first when the screen arrives — the expense that gets photographed — and again when the sound arrives, the expense that gets heard. In between sits the item almost everyone forgets: the room, which gives back half of what you listen to. This calculator lines up the three true chapters — video, audio, acoustics — over the room's area, and judges them with the metric installers have always used: the audio/video ratio. Because home cinema almost never fails on the wrong screen: it fails on the ear treated as a guest.

The formula: three chapters and two compasses

The model is the structure of every honest AV quote: C = V + U + A·t — the video chapter, the audio chapter and the acoustic treatment scaling with the room's square metres (rugs, heavy curtains, panels at the reflection points). From here the two compasses: the ratio ρ = U/V, dimensionless, saying who commands between sound and picture, and the acoustic share q_a = 100·A·t/C, measuring how much of the project is devoted to the room. The first is the compass of balance; the second, the one separating true theaters from rooms with equipment inside.

The video scale: the screen grows, the ratio collapses

Audio steady at 1,500, a 20-metre room with medium treatment; only the video chapter grows:

The same audio goes from «listening room» (3.00) to «mute system» (0.19) without anyone touching a speaker: the ratio is a proportion, and a screen growing alone flips it. The last row also lights the bare-room flag: at a 10,300 build, acoustics has dropped below ten percent — the reference projector will sound like the room hosting it.

A complete numerical example

The typical dedicated living room: 2,000 of video — an entry projector and screen, or a very large TV — 1,500 of audio for an honest 5.1 with subwoofer, 20 square metres with 40 per metre of treatment: a full rug, heavy curtains, four panels. The total closes at 4,300 — 215 per square metre — with an audio/video ratio of 0.75 and acoustics at 18.6 percent. It is the physiology of the well-made room: video commands by little, audio chases closely, and the room has its chapter — not yet the enthusiasts' full balance, but none of the three legs is lame.

How to read the audio/video ratio

Below 0.50, the system is mute: more than two units in picture for every unit of sound — cinema picture with television audio, the most widespread flaw of home rooms. Between 0.50 and 1.00, video commands and audio chases: the physiology. Between 1.00 and 1.50, the balance of the room: sound and picture as equals, the proportion enthusiasts defend. Beyond 1.50, the listening room: the audiophile's signature. And across all bands, the room threshold: when acoustics drops to ten percent or below, the calculator flags the bare room — because from there down, the best system sounds like the room.

Acoustics: the item with the best yield per spend

Acoustic treatment is the least photogenic and most profitable chapter of the project. It is not soundproofing — that isolates the room from the neighbours, and has its own dedicated calculator — but the sound inside the room: the rug that kills the floor, the curtains taming the glazing, the panels at the first reflection points, the bass traps in the corners. The physics is simple: in a live room half of what you hear is reflection — and the reverberation time calculator measures it. The practical rule: from 30 to 60 per square metre buys eighty percent of the benefit; the bare room, at any level of equipment, returns live echoes, bloated bass and smeared dialogue.

The video chapter: screen or projector

Below 2,000, the video chapter is almost always a large TV: bright, maintenance-free, perfect in rooms that cannot be darkened. From the projector up, the nature of the expense changes: to the unit you add the screen, the lamp or laser over time, and above all the dark — because the projector buys inches at unbeatable prices but pays for them in light control. The right question is not «how big?» but «how dark can the room be?»: in lived-in rooms the 500-1,500 TV often beats the 3,000 projector — and the audio/video ratio says thanks.

The audio chapter: channels before watts

The audio chapter's hierarchy is counterintuitive: first the right channels in the right places — a well-positioned 5.1 beats a 7.2 dropped wherever it fits — then the quality of the front pair and the centre, which carries the dialogue, and only at the end the watts. The subwoofer deserves its own rule: its yield depends on position more than price, and half an hour of corner experiments is worth a model up. It is the chapter where quality second-hand yields most — speakers age well — and where the final calibration, with measured levels and distances, is the whole project's free multiplier.

International perspective, limits and correct use

The model is currency-neutral and the ratio is dimensionless: 0.75 tells the same proportion in every market, and the video-audio-acoustics structure is that of every room in the world — price lists change, the project's legs do not. The limits are declared: the bill does not include seating and furnishing, blackout, dedicated electrics or automation — real items that in serious rooms add a whole chapter — and it does not measure quality inside the chapters: two thousand spent well and two thousand spent badly weigh the same here and very differently in the room. And the order reminder holds: first the room, then the equipment — because an electronics upgrade takes an afternoon, an acoustics one does not. Final confirmation belongs to listening: here is the honest arithmetic of the three legs.

The audio scale: from mute to listening room

Video steady at 2,000, a 20-metre room treated at 40; only the audio chapter grows:

The 3,000 row lands exactly on the 1.50 border: the serious system is, by the model's definition, the entrance to the listening room. And the last row teaches the calculator's finest lesson: the 6,000 audio lights the bare-room flag — the build has grown so much that the treatment stuck at 800 has slipped below ten percent: even the audiophile signature, in a room left behind, sounds like the room.

The treatment scale: the item that scales alone

The same 3,500 bare system; only the treatment per square metre grows:

The audio/video ratio stays still at 0.75, five times over — the speakers do not know which room it is — while the acoustic share climbs from zero to 40.7. The first row carries the flag; the second brushes and escapes it: 10.3 against the threshold of ten — a rug and two curtains suffice to leave the bare room. And it is the calculator's cheapest scale: from 3,500 to 4,300 lie eight hundred units, and inside them sits eighty percent of the whole room's acoustic benefit.

The areas and the ten-percent quadruple

With the system steady, the area works in two directions: the 10-metre room concentrates the spend (390 per metre) but its treatment is worth only 10.3 percent — again one decimal from the flag — while the 30-metre room drops to 157 per metre with acoustics at 25.5: the large room dilutes the cost and enriches the sound, because square metres bring treatment along. And on the flag's exact border lives the signature pair: the 4000-3200-20-40 build closes at a round 8,000 with the acoustic share at an exact 10.0 — flagged by a whisker — while the 3,900-video twin escapes at 10.1: between the bare room and the dressed one, in the model, lie one hundred units of screen.

The exact borders and the extremes

The ratio's three borders can all be touched by hand: 0.50 with the thousand 5.1 on the two-thousand projector; 1.00 with the perfect 2,000-and-2,000 balance; 1.50 with the first table's three thousand of audio. At the extremes, the model's two worlds: the 900 essential corner — TV, soundbar, bare room: flagged, and rightly so — and the 18,800 maximum room, which with acoustics at 25.5 and ratio 0.75 is not flagged: as in the funeral calculator, the bill does not punish size — it punishes imbalance.

The mistakes you can hear

Three recurring mistakes, in order of frequency. First: the whole budget on the screen — the video scale shows it: the ratio collapses from 3.00 to 0.19 without touching a speaker, and the reference picture arrives with television sound. Second: confusing soundproofing and treatment — absorption panels do not stop the bass crossing the neighbour's wall, and acoustic insulation does not dry the reverb: two problems, two projects, two budgets. Third: buying the upgrade before the calibration — levels, distances and subwoofer position are the free multiplier: yesterday's calibrated system almost always beats today's untuned new one.

Three strategies for the right room

First: build with even legs — every screen jump gets its sound jump, and every system jump its room jump: the ratio and the acoustic share are the two lights to keep green together. Second: spend the eight hundred of basic acoustics first — rug, curtains, four panels: no other item in the project buys as much yield, and the treatment scale proves it row by row. Third: leave a chapter for the dark and the seats — the off-model items (blackout, seating, electrics) are the ones that turn a system into a theater: whoever forgets them has bought a cinema and furnished a closet.

Frequently asked questions

How much does a home theater cost?

It hangs on three chapters: video, audio and acoustics over the area. The model's typical room — 2,000 of video, 1,500 of audio, 20 metres treated at 40 — closes at 4,300, that is 215 per square metre. The real range runs from the 900 essential corner to the model's 18,800 maximum room.

What is the audio/video ratio?

The audio chapter divided by the video chapter: the compass of balance. Below 0.50 the system is mute (cinema picture, television sound); between 0.50 and 1 video commands; between 1 and 1.50 the balance of the room; beyond 1.50 the audiophile's listening room.

When does the bare-room flag fire?

When the acoustic treatment is worth ten percent of the total or less — zero included. It is physics' reminder: in a live room half of what you hear is reflection, and the best system sounds like the room hosting it.

Are acoustic treatment and soundproofing the same thing?

No, and it is the trade's dearest confusion: soundproofing isolates the room from the neighbours (mass, decoupling, building work), treatment governs the sound inside (rugs, curtains, panels, bass traps). This calculator measures the second; for the first there is the soundproofing calculator.

How much acoustic treatment is needed?

The model's practical rule: 30-60 per square metre buys eighty percent of the benefit — full rug, heavy curtains, panels at the first reflection points, corner traps. From 80 to 120 you enter designed treatment with measurements: the dedicated rooms' band.

TV or projector?

The right question is how dark the room can be: the projector buys inches at unbeatable prices but pays in light control; the TV wins in lived-in, bright rooms. Below 2,000 of video chapter, the large TV is almost always the honest answer.

How is the audio chapter spent well?

Channels before watts: a well-positioned 5.1 beats a 7.2 dropped anywhere. Then fronts and centre (it carries the dialogue), the subwoofer chosen by position more than price, and the final calibration with levels and distances: the chapter's free multiplier.

Why does buying a bigger screen worsen the ratio?

Because the ratio is a proportion: with audio steady, video going from 500 to 8,000 collapses ρ from 3.00 to 0.19 without touching a speaker. It is the table's lesson: balance is not bought on one chapter — every screen jump asks for its sound jump.

What does the cost per square metre say?

How dense the room is: 140-200 per metre is the AV corner in the living room, 200-350 the entry dedicated room, beyond 400 the serious project. It is the lens for comparing rooms of different sizes — and for seeing whether spend grows with the room or only with the gear.

In what order should the room be built?

First the room (dark, rug, curtains, first panels), then the audio positioned and calibrated, finally the electronics upgrades. The reverse order pays twice for the same flaw: a projector upgrade takes an afternoon, an acoustics one does not.

Does the calculator work in any currency?

Yes: the four items are pure numbers in your currency and the metrics are dimensionless — the 0.75 ratio and the 18.6 acoustic share tell the same proportions in Milan, London or Sydney. Price lists change, the project's legs do not.

What does the calculation NOT cover?

Seating and furnishing, blackout, dedicated electrics, automation and sources — real items that in serious rooms add a whole chapter — and the quality inside the chapters: two thousand spent well and two thousand spent badly weigh the same here. Confirmation belongs to listening in the room.

Updated July 2026