What I would actually buy: four for the bedrooms — ₹7,596, twelve 15ml scents included — and a Vaayu for the common areas instead of the fifth and sixth tank.
Why they diverge: the count measures doors. It does not measure how many tanks a household will still be filling in March.
2. Four is the number I would actually buy — ₹7,596. One in each bedroom, with twelve 15ml Hotel Collection bottles arriving between them. Every bedroom in a 4BHK sits comfortably inside the rating, so these four machines are doing easy work on their lowest setting and each belongs to one person.
3. The fifth and sixth machines are the ones to argue about. The fifth stands in a 450–700 sq ft living-dining that is between one and a half and two and a half times its rating; the sixth stands in a study somebody may or may not sit in. Neither is a bad machine in a bad room — they are the two purchases that turn a habit into a rota.
4. Spend the fifth and sixth machine's money on the right machine instead. A waterless Vaayu at ₹11,999 — up to 1000m³ of connected space, no tank, no added humidity, under 38dB, Bluetooth app with genuine scheduling — takes the living, dining, entrance and corridor as one volume. Four Sukoons and a Vaayu is ₹19,595.
5. Kitchens, bathrooms, balconies and corridors still do not count. You pass through them rather than live in them. A bathroom is served by a Boond at ₹899, a corridor borrows from the rooms either side of it, and a bedroom nobody sleeps in wants a reed diffuser from ₹749 rather than a fifth tank.
A portion of every order supports girl-child education through Nanhi Kali.
The counting rule at five and six doors
I have given the same rule at every home size in this cluster and it has held up without amendment: walk the flat in the evening, count the doors you shut behind you and then stay behind, and that number is your machine count. A studio returns one, a 1BHK two, a 2BHK three, a 3BHK four. A 4BHK returns five or six, and this is the size at which the rule starts describing a floor plan more accurately than it describes a household — because the thing it has never measured is how much weekly work the answer creates.
How many, by 4BHK layout and household
4BHK is a label rather than a floor plan, and the same four bedrooms behave completely differently depending on who is asleep in them. Find the row that describes your flat and your household honestly rather than aspirationally — the middle column is what I would say across a table, not what a price list would.
| Your 4BHK | The honest number | Where they go | Cost |
|---|---|---|---|
| Couple or small family, two bedrooms slept in, walled living-dining | Two or three Sukoons | The bedrooms in use plus the living-dining; reeds in the rooms that wait | ₹3,798–₹5,697 |
| Family of four, all bedrooms used, open living-dining ★ | Four Sukoons + one Vaayu | One machine per bedroom, twelve 15ml scents; the common areas on the waterless machine | ₹19,595 |
| Family of four, all bedrooms used, walled 450 sq ft living-dining | Five Sukoons | One per bedroom plus the living-dining centrally at 90–120cm — fifteen 15ml scents | ₹9,495 |
| Joint family, four bedrooms plus a study somebody works in | Four Sukoons + one Vaayu, or six Sukoons | Bedrooms and study on ultrasonic; the common areas on whichever machine you chose | ₹19,595 or ₹11,394 |
| Two bedrooms genuinely slept in, two kept for visitors | Two Sukoons + one Vaayu | The two lived-in bedrooms and the connected common areas; a reed duo at ₹1,598 in the waiting rooms | ₹15,797 |
| Double-height or 600–700 sq ft open living, dining and entrance | Bedrooms on Sukoons, common areas on a Vaayu | Never two ultrasonic units in one open volume — they overlap in the middle rather than reaching the ends | ₹15,797–₹19,595 |
Sukoon · one per closed door₹1,899Shop → 
Hotel Collection · 7 scentsfrom ₹299Shop → 300ml refill · five tanks, one bottle₹1,799Shop →
Where the honest answer leaves the count behind
Start with the machine nobody argues about, because four of the five are genuinely easy. Each bedroom in a 4BHK — a 160–220 sq ft master and three rooms of 110–160 — sits comfortably inside a Sukoon's 270–320 sq ft rating, which means those machines are never working hard. A bedroom unit runs on low with the 2H timer, placed across the room from the pillow and at least 1.5m away, and a single 500ml fill lasts most of a week at that setting rather than the 16–18 hours a continuous run would give you. Four of them is ₹7,596 and arrives with twelve 15ml Hotel Collection bottles of your choice, which is the arithmetic people leave out: the fourth machine buys a room and a third of a fragrance wardrobe, so it never feels like buying the same thing again. It also buys the thing this home size is genuinely about, which is autonomy. Four bedrooms with four machines is four people each choosing what their own room smells of — the teenager on something dry and green, the guest on something deliberately neutral, you on amber behind a shut door at eleven at night. That is not a feature you can buy from a central system at any price, and it is the strongest argument for ultrasonic machines in this house.
Then the fifth machine, which is where I stop agreeing with my own rule. The fifth Sukoon goes into the living-dining, and a 4BHK living-dining is 450–700 sq ft — between one and a half and two and a half times what one unit is rated for, and usually not even a room but a living area, a dining area and an entrance with the corridor opening off one end and no door in the whole arrangement. Try the free fixes first, because they genuinely help and cost nothing: raise the unit to 90–120cm on a console, since cool mist is denser than room air and descends as it spreads, then move it central to the volume and onto the line the air already takes, front door to balcony. At the tidy end of 450 sq ft that can be enough. Past that it is not, and the instinct to add a sixth unit at the far end of the same space is the commonest expensive mistake at this size — two ultrasonic machines in one air mass overlap in the middle rather than adding their ratings together, so the centre gets heavier and the ends stay much as they were, and you have spent ₹1,899 to achieve that. A waterless Vaayu at ₹11,999 is the machine for that volume: a cold-air nebuliser running undiluted oil rather than water, rated for up to 1000m³ of connected space, adding no humidity, running under 38dB, with a Bluetooth app and genuine scheduling. Four Sukoons and one Vaayu is ₹19,595.
Now the part I would most like people to weigh before ordering five or six machines, because it does not appear on any invoice. A 500ml tank wants emptying, rinsing and a wipe at the misting plate on a regular morning, with filtered or RO water if your city is hard-water. One machine is a pleasure. Three is a routine that takes about ten minutes. Five is a rota, and six is a job — and the failure mode is not a badly scented home but four machines standing quietly dry from about March while the household concludes that home fragrance was a phase. If you are set on the Sukoon-only route, the version I would defend is five at ₹9,495 with all of them done on one morning rather than reactively, and I would point out that five machines plus a 300ml 300ml refill is ₹11,294 — a hundred rupees less than six machines at ₹11,394, and it improves rooms you already run rather than adding one you do not. For the bedroom nobody sleeps in, a reed diffuser from ₹749, the 130ml at ₹1,299 or the duo set at ₹1,598 reads as looked-after rather than shut up, for a fraction of a machine and none of the labour. And the two upgrades people ask about here both miss: the Megh at ₹3,499 is a fine 6-litre unit that solves refill frequency in one large space and still occupies exactly one room, and the Aangan at ₹25,999 is an HVAC nebulising system for 8,000–10,000 sq ft, which is a hotel floor rather than a home.
The SOSA 4BHK edit
The count as a shopping list, arranged so you can start at any line and move down it over months without anything you already own becoming redundant. The last row is the one the arithmetic recommends and I do not.
| Buy | What it adds | When | Price |
|---|---|---|---|
| 1. Four Sukoons, one per bedroom ★ | The four rooms that close, each on a fragrance its occupant chose — twelve 15ml Hotel Collection bottles between them | First. Two at ₹3,798 is the honest floor if only two bedrooms are slept in | ₹7,596 |
| 2. Vaayu for the common areas | Up to 1000m³ of connected space with no tank, no added humidity, under 38dB and real app scheduling — the living, dining, entrance and corridor as one volume | Instead of the fifth and sixth Sukoon, once the bedrooms are running | ₹11,999 |
| 3. 300ml refill | Your everyday scent across every ultrasonic tank at roughly ₹6 per ml against about ₹20 per ml in 15ml bottles | After a month, once one of the twelve included bottles has won | ₹1,799 |
| 4. Reed diffuser or duo set | The bedroom nobody sleeps in, given a quiet presence with no socket, no tank and no routine | Instead of a machine in a room used four times a year | from ₹749 / ₹1,598 |
| 5. Boond 300ml | A bathroom at the right scale, on the fragrance bottles you already own | Only after every room you are awake in has something | ₹899 |
| What the count says: five or six Sukoons | Every enclosed volume covered on paper — and five or six tanks to empty, rinse and refill weekly | Five at ₹9,495 is defensible; six at ₹11,394 is the number I would talk you out of | ₹9,495 / ₹11,394 |
Versailles
People expect me to answer this with a coverage table and are usually a little disappointed when I answer it with a walk around their own flat and a question about their Sunday mornings. But the table is the thing that misleads at this size. A coverage figure describes connected air, and an Indian 4BHK is about as disconnected as homes get — five or six volumes, five or six doors, and those doors shut for most of the hours that matter.
So count the doors, and then count the mornings. The rule gets a studio to one, a 1BHK to two, a 2BHK to three, a 3BHK to four and a 4BHK to five or six. This is the first size where I will overrule it, because the fifth and sixth machines are the two that turn a pleasure into an obligation, and one of them is standing in a room it was never rated for anyway. Buy four for the bedrooms, put four different fragrances in them, and then decide about the common areas with clear eyes — a waterless machine at ₹11,999 if the space is genuinely open and you want it scheduled and tank-free, or nothing at all if the doors usually stand open and the four bedrooms are doing the work. Both of those are honest answers. Six tanks is not.
Everything is made and supported from Pune, and a part of every order funds girl-child education through Nanhi Kali. You get a home that smells like somewhere you chose; a girl gets a classroom. That equation has always felt right to me.
Frequently asked questions
- Is an ultrasonic diffuser enough for a large 4BHK? — where the coverage maths stops working.
- Should every bedroom in a 4BHK have its own Sukoon? — the autonomy argument, in full.
- Where should you place multiple ultrasonic diffusers in a 4BHK? — placement for four to six units.
- The complete SOSA home fragrance buying guide for a 4BHK — the pillar guide.
- Brand: the SOSA founder story.
Facts verified August 2026: SOSA Sukoon — 500ml tank, 2.4MHz ultrasonic cool mist, 270–320 sq ft coverage, 16–18 hours runtime on low and 9–12 on high, 30–50 ml/h mist output, 7-colour LED, remote and steady/2H/4H timers, BPA-free ABS with auto shut-off and overheat protection, ~17cm high — ₹1,899, including three 15ml Hotel Collection fragrances of your choice. Boond 300ml ₹899; Megh 6-litre ₹3,499. Hotel Collection water-based fragrance 15ml ₹299, 100ml ₹999, 300ml ₹1,799, Pack of 7 × 15ml ₹1,799; 100ml and 300ml refills from ₹999. Seven scents: The Ritz-Carlton-inspired (white tea, bergamot, cedar), Westin-inspired (white tea, aloe, cedar), 1 Hotels-inspired (cedarwood, vetiver, green leaves), The St. Regis-inspired (amber, violet, woods), Shangri-La-inspired (jasmine, green tea, white tea), Four Seasons-inspired (citrus, floral, sandalwood), W Hotels-inspired (citrus, pepper, amber). Waterless systems for larger and connected spaces: Vaayu ₹11,999 (up to 1000m³), Aangan ₹25,999 (8,000–10,000 sq ft), Meenar ₹38,500 (12,000–18,000 sq ft). The Hotel Collection scents are SOSA's own interpretations; SOSA is not affiliated with or endorsed by any hotel brand. Prices subject to change — see the live product pages.