How many access points does a 3 BHK need?

You're standing in the third bedroom with one bar, and the router is in the meter cupboard by the front door where the technician left it. The question that follows is always the same: how many more boxes do I need to buy?

For most 3 BHK flats in Mumbai and Thane, the answer is two access points in total — one at the living end, one behind the bedrooms. A large 3 BHK, or one where the incoming line lands in a far corner, usually needs three. A compact, open 3 BHK sometimes needs one, provided that one is in the right place. The rest of this is why it is a range, and how to place your own flat in it.

Walls decide the answer, not floor area

Two flats on the same floor of the same tower, identical carpet area, can need different counts. The difference is what the signal has to cross.

An indoor router in India is allowed 100 mW EIRP, and the signal has to arrive above a usable floor: −67 dBm is the standard design threshold for calls and video. That leaves roughly 87 dB of budget to spend on the journey. And −67 dBm is a floor for how loudly the signal arrives, not for how clearly it is heard: in a building full of neighbouring networks the gap between signal and noise closes first, which is why two flats can show identical bars and behave nothing alike. A reinforced concrete wall takes about 54 dB of it at 5 GHz on NIST’s measurements of real specimens, and open air spends the rest faster than you would think. One RCC wall plus a short walk down a passage and the budget is gone. A plasterboard partition costs almost nothing, an open doorway nothing at all.

So the count follows the floor plan, not the square footage. Count the concrete between the router and the furthest place you actually use the internet.

The 950 sq ft rule of thumb, and where it breaks

One router covers about 950 sq ft in a concrete Indian home. I use that figure on the coverage check on the homeowners page. It is a reasonable first guess, not a measurement of yours.

It is optimistic when the internal walls are RCC rather than brick, when full-height mirrored wardrobe doors sit in the way — the coating behind the glass reflects rather than passes — when the router is shut inside a metal meter cupboard, and, most often, when the line enters at one corner of the flat. A router in the corner spends half its coverage on the lift lobby and your neighbour’s kitchen. The 950 assumes it is all spent inside your home.

It is pessimistic when the living and dining are one open space with no wall between them, when a recent fit-out used drywall partitions instead of block work, and when the line enters near the middle of the flat or can be extended there with one cable run.

Working it through, flat by flat

A compact 2 BHK, 800 to 1,100 sq ft. On paper one unit nearly covers it; in practice the router is at the entrance and the master bedroom is at the far end behind a passage and two walls. Often the right answer is not a second box but moving the first one: a short cable run to the middle of the flat. If the far bedroom is still behind concrete, one more unit, wired, finishes it.

A standard 3 BHK, 1,200 to 1,500 sq ft. The arithmetic says one router plus one access point covers the area, so two. The layout usually agrees, because the three bedrooms tend to open onto a single passage: a ceiling unit in that passage reaches each bedroom through a doorway rather than through a wall. That is the common case. It goes to three when the master sits beyond a turn in the passage, or the kitchen and utility hide behind their own concrete.

A large 3 BHK above 1,500 sq ft, or a duplex over two floors. A slab is a wall you cannot walk around. Signal doesn't turn corners through a slab because you hoped it would, and it won't climb one for you either. Start from one unit per floor, then add one for whichever end is far from the stairs. Three for a large flat on one floor, four once there is a second.

A villa. Same logic, more floors, and the grounds are their own exercise. Four and upwards, at least one outdoor-rated.

Two well-placed units beat four badly placed ones

The real question is not how many access points your flat needs. It is how many places in your flat can see enough rooms to be worth mounting one. A ceiling unit in a passage sees every room that opens onto that passage. A unit in the corner of a bedroom sees one bedroom and a wall. Those are not the same purchase.

The same goes for how they are fed. An access point on a cable delivers what it is given. One that has to pick the signal up from another access point is listening and re-sending on the same radio it serves you with, so about half of what it receives is what you get. A mesh unit with a radio set aside for the backhaul does better than that, and still not as well as a cable. Wired backhaul is the single biggest difference between real coverage and a chain of repeaters fighting each other.

More access points is not more WiFi

WiFi on a channel is one conversation at a time. Two access points on the same channel that can hear each other take turns; they do not talk over one another, they wait. Add a third with overlapping coverage and the same airtime is divided more ways. On 2.4 GHz in a Mumbai tower you are already sharing with the whole building before you add anything of your own.

Put four units at full transmit power into a 1,400 sq ft flat and every device can hear all four from anywhere. Phones then cling to whichever one they joined first and refuse to hand over, which is the symptom the extra units were bought to cure. Sorting that out is channel planning, transmit power set down rather than up, band steering and fast roaming: work, not hardware. Four at full power is worse than two done properly.

Terraces, balconies and duplex staircases are counted separately

An indoor access point leaking through a glass door is not terrace coverage. It is the reason the call drops when you step outside. Anything outdoors — terrace, balcony, garden, the landing on a duplex staircase — wants an outdoor-rated unit and a proper cable entry, and it belongs in the count as its own line. Worth settling before the false ceiling closes, which is why cable routes are easier to place during a fit-out than after one.

The count comes out of the survey, not out of a table

Every number above is a starting guess. The one that ends up in your plan comes from walking your flat with a meter: signal and interference measured room by room, the incoming line and the existing hardware checked, and then a written plan with the count, the placement and the cable routes before anything is bought.

Sometimes that plan says one access point. Sometimes it says none, and the fix is getting the router out of the meter cupboard. If your flat needs two and you have been quoted four, the extra two are not coverage — they are two more radios waiting for a turn to speak.