How Many Rooms Can One 300ml Refill Keep Going?

How Many Rooms Can One 300ml Refill Keep Going?

★ ★ Honest sizing · what a refill actually covers50ml ₹749 · 130ml ₹1,249 · Duo ₹1,498 · Sukoon ₹1,899A portion funds girl-child education
★ Sizing and quantity · refill arithmetic
One room for about eight months, or two rooms for about four — plus forty millilitres you have to plan for
300ml divided by 130ml is 2.3 fills. Not three, not two — two full fills and a remainder of 40ml.
The division
2.3 fills, not 3
One room on six reeds: two fills is 32 weeks, and the 40ml adds about five more. That is roughly eight months from one ₹2,399 refill.
One room
About eight months
Two rooms on six reeds: one fill each, so about sixteen weeks apiece. Call it four months each before you are buying again.
Two rooms
About four months each
₹2,399 for 300ml is ₹8.00 a millilitre against ₹9.61 in a new 130ml bottle. A fill costs ₹1,040 instead of ₹1,249.
The saving
₹209 a fill
Waste the last 40ml and the real price becomes ₹9.23 a millilitre — a saving of four per cent instead of seventeen, and no new glass.
The remainder problem
17% falls to 4%
The 500ml at ₹3,499 is ₹7.00 a millilitre and gives three full 130ml fills with 110ml over. That is the three-room refill.
When to size up
₹7.00 a millilitre
300ml divided by 130ml is 2.3 fills. Not three, not two — two full fills and a remainder of 40ml.
The division
2.3 fills, not 3
One room on six reeds: two fills is 32 weeks, and the 40ml adds about five more. That is roughly eight months from one ₹2,399 refill.
One room
About eight months
Two rooms on six reeds: one fill each, so about sixteen weeks apiece. Call it four months each before you are buying again.
Two rooms
About four months each
₹2,399 for 300ml is ₹8.00 a millilitre against ₹9.61 in a new 130ml bottle. A fill costs ₹1,040 instead of ₹1,249.
The saving
₹209 a fill
Waste the last 40ml and the real price becomes ₹9.23 a millilitre — a saving of four per cent instead of seventeen, and no new glass.
The remainder problem
17% falls to 4%
The 500ml at ₹3,499 is ₹7.00 a millilitre and gives three full 130ml fills with 110ml over. That is the three-room refill.
When to size up
₹7.00 a millilitre
SOSA reed diffusersReeds from ₹749 SOSA Day and Night reed diffuser duoDuo ₹1,498 SOSA Sukoon 500ml ultrasonic diffuserSukoon ₹1,899 SOSA reed diffuser refillsRefill ₹2,399 SOSA Hotel Collection fragrancesScents ₹299
★ See the reed diffuser refills ₹2,399 Two rooms — the duo ₹1,498
✓ Honest coverage figures — six reeds, up to about 150 sq ft, not "a whole home" ✓ 50ml ₹749 for 6–8 weeks · 130ml ₹1,249 for 14–18 · every total on this page adds up ✓ Most homes need fewer units than they expect — we will say so

 

Founder Diaries · Sizing and quantity
By Sonal Sahani · ISIPCA Versailles 10 min read Updated August 2026
2.3. That is 300 divided by 130, and it is the number the whole question turns on. One 300ml refill at ₹2,399 gives you two complete fills of a 130ml bottle and a remainder of forty millilitres — so it keeps one room going for about eight months, or two rooms for about four months each. It does not stretch to three rooms, whatever the millilitres suggest, and what you do with the last forty millilitres decides whether you saved seventeen per cent or four.
Quick answers — read this first
One room: about eight months. Two fills is 32 weeks on six reeds, and the 40ml remainder adds roughly five more.

Two rooms: about four months each. One fill apiece, sixteen weeks, and then you are ordering again.

Three rooms: not really. Two rooms get a full fill and the third gets 40ml. For three rooms the 500ml at ₹3,499 is the honest size — three full fills, 110ml over, and ₹7.00 a millilitre.
The short answer
Short answer: One room for about eight months, or two for about four each. A 300ml refill at ₹2,399 divides into a 130ml bottle 2.3 times — two full fills plus 40ml — and a 130ml on six reeds runs 14–18 weeks. Two fills is roughly 32 weeks; the remainder adds about five more.
The price per millilitre: ₹2,399 ÷ 300 = ₹8.00 a millilitre. A new 130ml bottle at ₹1,249 is ₹9.61 a millilitre. So each fill costs ₹1,040 instead of ₹1,249 — a saving of ₹209, or about seventeen per cent, and you keep the glass and collar you already own.
The catch nobody mentions: If the last 40ml sits in a cupboard and is never used, your real cost is ₹2,399 over 260ml, which is ₹9.23 a millilitre — a saving of four per cent rather than seventeen, and no new bottle to show for it. Planning the remainder is most of the value of buying a refill at all.
In this guide
The unit
One reed diffuser · from ₹749
Two rooms
Day & Night duo · ₹1,498
Large rooms
Sukoon 500ml · ₹1,899
Straight answer
How many rooms can one 300ml reed diffuser refill keep going?
1. One room for about eight months. Two full 130ml fills at 14–18 weeks each — call it sixteen — is 32 weeks. The 40ml remainder in the same bottle is roughly 31 per cent of a fill, which on six reeds is about five more weeks. Total: around 37 weeks, or a shade over eight months, from one ₹2,399 refill in one room run continuously.

2. Two rooms for about four months each. Split the same refill between two 130ml bottles and each gets one fill of sixteen weeks. That is about four months apiece, and then both rooms want liquid at roughly the same moment — which is the argument for staggering your reed counts rather than your orders. Run one room on six reeds and the other on four and they will finish about five weeks apart instead of together.

3. Three rooms, honestly, no. Three 130ml bottles need 390ml to fill once. A 300ml gives two of them a full fill and the third 40ml — about five weeks. If you genuinely run three bottles of the same scent, the 500ml at ₹3,499 is the right size: three complete fills with 110ml over, at ₹7.00 a millilitre against ₹8.00.

4. On fewer reeds, everything above stretches. Reed count is the volume dial and it changes these numbers more than anything else. A 130ml on four reeds runs towards twenty-one weeks rather than sixteen, so two fills plus the remainder becomes roughly 48 weeks — very nearly a full year of one room from a single refill. On two reeds in a bathroom it goes well past a year.

5. And the last 40ml is not a rounding error. It is ₹320 of liquid at ₹8.00 a millilitre. Left in the cupboard it turns a seventeen per cent saving into four per cent, because your effective price becomes ₹2,399 over 260ml, or ₹9.23 a millilitre against ₹9.61 for a brand-new bottle with new glass. The fix is to top up rather than wait for empty — the method is below.

Made in India, composed by an ISIPCA Versailles-trained perfumer — and a portion of every order supports girl-child education through Nanhi Kali.
TL;DR: a 300ml refill at ₹2,399 divides into a 130ml bottle 2.3 times, so it keeps one room going for about eight months or two rooms for about four each. It does not do three rooms — that is the 500ml at ₹3,499, which gives three full fills at ₹7.00 a millilitre. And plan for the 40ml remainder: wasted, it turns a seventeen per cent saving into a four per cent one.
SOSA reed diffuser refills
The running cost, solved
300ml Refill ₹2,399
A 300ml SOSA reed diffuser refill at ₹2,399 is ₹8.00 a millilitre against ₹9.61 in a new 130ml bottle, so each fill costs ₹1,040 instead of ₹1,249. Two full fills and 40ml over. The 500ml at ₹3,499 is ₹7.00 a millilitre and gives three fills. Refilling is also the moment to fit fresh reeds — clogged fibre is the commonest reason throw drops off.
See refills →

Why the answer is 2.3 fills, not three

Divide 300 by 130 and you get 2.31. That is the whole arithmetic, and it is worth doing deliberately because the round numbers on the labels invite a different conclusion. A 300ml sounds like it should serve three rooms of 100ml each, or three bottles, or a season for a whole flat. It does not: it is two complete fills of a 130ml bottle plus forty millilitres. Convert that to time and it depends entirely on reed count, because reed count is the only volume control a passive diffuser has and it sets consumption as well as strength. On six reeds a 130ml runs 14–18 weeks, so two fills is roughly 32 weeks and the remainder — about 31 per cent of a fill — adds about five more. Around 37 weeks in one room, which is a little over eight months. On four reeds the same 130ml runs towards twenty-one weeks, so the same refill covers about 48 weeks, which is very nearly a year. Nothing about the refill changed; you simply asked the bottle to work less hard.

The second thing worth doing deliberately is the price per millilitre, because it is the only fair way to compare a refill against a bottle. ₹2,399 over 300ml is ₹8.00 a millilitre. A new 130ml bottle at ₹1,249 is ₹9.61. So a fill from a refill costs ₹1,040 against ₹1,249 for new glass — a saving of ₹209, or roughly seventeen per cent, on the reasonable view that the bottle, the collar and the reeds were always the durable part and you did not need another set. The 500ml at ₹3,499 is ₹7.00 a millilitre, which is better again, and it divides into 130ml 3.85 times: three complete fills with 110ml left, a remainder that is 85 per cent of a fill rather than 31 per cent. That proportion is the real reason the larger refill suits a three-bottle house — not the headline price.

One room, two rooms, and what to do with the last forty millilitres

1
ONE ROOM · ABOUT EIGHT MONTHS
Two fills, a remainder, and 37 weeks
SOSA reed diffuser refills300ml refill₹2,399The simplest and best use of a 300ml is a single room you care about. Two fills at sixteen weeks each on six reeds is 32 weeks, and the 40ml remainder adds roughly five, so you are buying about eight months of a living room for ₹2,399 — a bit under ₹65 a week. Drop to four reeds and the same refill covers about 48 weeks, or a shade under ₹50 a week, which is the cheapest way to run any single room in the range. One order, one scent, one bottle, and a decision you make roughly once a year rather than three or four times.
Best for: a living room or entrance you have already settled on, where you are not going to want to change the blend for a year.
2
TWO ROOMS · ABOUT FOUR MONTHS EACH
One fill apiece, and a staggering problem
Split a 300ml between two 130ml bottles of the same scent and each room gets sixteen weeks on six reeds — about four months. That works, and it is the commonest real use, but it introduces a small problem worth planning around: both bottles now run out at roughly the same time, so you get one large reorder instead of two small ones and a fortnight where the house smells of nothing while you wait. The fix costs nothing. Run the two rooms at different reed counts — six in the living room and four in the bedroom — and they will finish about five weeks apart, which turns one awkward gap into two manageable ones. The 40ml remainder then goes to whichever bottle empties first, as a bridge.
The trade: two rooms halves the interval, not the cost. Four months each instead of eight for one, at the same ₹2,399.
3
THE REMAINDER · ₹320 YOU CAN EASILY WASTE
Top up early rather than wait for empty
Forty millilitres at ₹8.00 a millilitre is ₹320 of liquid. If it stays in the cupboard because there is never quite a bottle empty enough to take it, your effective price becomes ₹2,399 over the 260ml you actually used — ₹9.23 a millilitre, against ₹9.61 for a brand-new bottle that came with new glass and new reeds. The saving collapses from seventeen per cent to four, which is not worth organising your cupboard around. The answer is to stop waiting for empty. Top the bottle up whenever it is about two-thirds down, and the same 300ml goes in across three top-ups instead of two fills and an orphan. A second, equally good answer is to keep a small bathroom bottle in the same scent: 40ml on two reeds runs it for about nine weeks.

Sizing by space — what one 300ml refill covers

All figures assume a 130ml bottle and a room run continuously; the cost column is what the refill works out at per week for that arrangement. One row recommends buying no refill at all.

The refill table
What one 300ml at ₹2,399 keeps going, and for how long
Space What it needs How many Cost
One room, 130ml on six reeds ★ Two full fills of 16 weeks plus about five weeks from the 40ml remainder About 37 weeks about ₹65 a room-week
One room, 130ml on four reeds Two fills of about 21 weeks plus about six from the remainder — very nearly a full year About 48 weeks about ₹50 a room-week
Two rooms, both 130ml on six reeds One fill each. Run them at different reed counts so they do not finish in the same fortnight About 16 weeks each about ₹75 a room-week
One 130ml and one small bathroom bottle on two reeds Two fills for the main room and the 40ml for the bathroom — the tidiest use of the remainder 32 weeks and 9 weeks about ₹58 a room-week
Three 130ml bottles of the same scent A 300ml cannot do this — buy the 500ml at ₹3,499 instead, three full fills at ₹7.00 a millilitre Wrong size — go to 500ml ₹3,499
Two or three bottles in different scents No refill yet. Each scent needs its own, so you would be buying ₹4,798 of liquid to keep two rooms going. Finish the bottles first None ₹0 for now
A note on all of the above: a refill is liquid only. It does not replace reeds, and clogged fibre is the commonest reason a refilled bottle throws less than a new one — fit fresh reeds every time you refill. Reed count changes every figure above by a wide margin, so treat these as six-reed numbers unless the row says otherwise.
Shop this guide
Two fills, forty millilitres, and the plan that stops it being wasted
SOSA reed diffusersOne room · the unitFrom ₹749Shop → SOSA reed diffuser duoTwo rooms · better value₹1,498Shop → SOSA Sukoon ultrasonic diffuserLarge room · a switch₹1,899Shop →
The SOSA principle
A 300ml refill is not three bottles. It is two bottles and a decision.
The decision is the last 40ml. Used, the refill saves seventeen per cent. Left in a cupboard, it saves four — and you did not get new glass either.

How to refill so that nothing is wasted

Top up at two-thirds down, not at empty. This single habit is what converts 2.3 fills into 2.3 fills of actual use rather than two fills and an orphan. When the bottle is around a third full, pour in roughly 90ml, and repeat. The 300ml then goes in across three visits and finishes cleanly, the room never has a fortnight of nothing while you wait for a delivery, and you never end up with a jug holding an amount too small to be worth opening. It also keeps the reeds continuously wetted, which matters more than people think: a reed that has stood dry in an empty bottle for a week wicks noticeably worse afterwards.

Fit fresh reeds every time you refill, and do not treat that as optional. A refill replaces liquid and nothing else. The fibre reeds clog gradually as the heavier fragrance molecules saturate the core, wicking slows, and throw drops off after a few months — at which point people top the bottle up, notice no improvement, and conclude the refill is weaker than the original bottle. It is not. The reeds are tired. Six fresh reeds come with every new bottle, so keep the spares from the ones you have already bought, and put in the same number you were running rather than taking the opportunity to add two, which would quietly cost you about ₹150 a reed over the bottle's life.

And decide the scent question before you buy the refill, not after. A refill is scent-specific, so it commits you to about eight months of that blend in that room. That is a good thing if the room is settled and a genuine trap if you are still deciding — which is exactly what the 50ml bottles at ₹749 are for. Buy refills for rooms you have lived with for a season and know you like: usually the living room and the bedroom. For a bathroom you enjoy changing, or a blend you are unsure of, keep buying small bottles. And store the jug sealed, upright, out of direct sunlight and away from heat, off polished wood, and well out of reach of children and pets.

A refill is two fills and a puzzle. The puzzle is the last forty millilitres.
— Sonal Sahani, SOSA

What to buy

The refill is a running-cost product, not a starting product — you need the glass first. This table is the order in which most homes actually arrive at it.

The refill edit
What to buy, and when the refill starts making sense
Buy What it covers Lasts Price
One 50ml A single reed diffuser — testing a blend before you commit eight months of refill to it 6–8 weeks from ₹749
One 130ml ★ The value size — the bottle a refill fills — the glass and collar are the durable part you are keeping 14–18 weeks from ₹1,249
The duo Day & Night duo — two rooms in one purchase, which is also the point at which a shared refill starts to work 6–8 weeks each ₹1,498
Sukoon 500ml ultrasonic — a large room where liquid is not the answer and a switch is Runs when you switch it on ₹1,899
300ml refill The running cost — one room for about eight months, or two for about four each — ₹8.00 a millilitre against ₹9.61 Roughly 2 × 130ml fills ₹2,399
Honest notes before you buy: every figure on this page is the real one and every total adds up — check them. Two things are worth saying plainly before you buy anything. First, coverage claims are steady-state figures: a reed diffuser on six reeds holds a room of up to about 150 sq ft when that room is closed and still. Open a balcony door, run a fan, or raise the ceiling to twelve feet and the same bottle covers noticeably less — not because it is weak, but because coverage is measured in a condition your home may not be in. Second, most homes need fewer units than they buy. A room nobody sits in does not need fragrance; a corridor is a transit space, not a room; and adding reeds to an existing bottle is free, while adding a bottle is not. Reed count is the volume dial — six for full strength, four for a bedroom, two or three for a small bathroom — and it is the first thing to try. SOSA reed diffusers are oil-based and composed and made in India, in Pune; the Sukoon (₹1,899) runs the water-based Hotel Collection (from ₹299) and the two liquids are not interchangeable. Both are phthalate-free and composed to IFRA standards for home diffusion, not for skin or ingestion. A portion of every order supports girl-child education through Nanhi Kali.
SOSA Day and Night reed diffuser duo
Two rooms, one purchase
Day & Night Duo ₹1,498
Two 50ml bottles — Morning Freshness and Evening Calm — at ₹1,498 against ₹1,548 bought separately. The saving is small; the real reason to buy it is that it solves two rooms at once with scents chosen to sit beside each other rather than argue.
See the duo →
SS
ISIPCA
Versailles
A note from Sonal

I put the division on the label in my own head years ago: 300 divided by 130 is 2.3. Not three. Every complaint I have ever had about refills traces back to somebody expecting three fills and getting two and a bit, and feeling short-changed by arithmetic that was on the box the whole time. So I would rather say it plainly at the top of the page than have you discover it with a jug in your hand.

The forty millilitres is the part I actually care about. It is ₹320 of perfectly good oil, and I have watched people leave it in a cupboard for a year because there was never a bottle empty enough to take it — which quietly turns a seventeen per cent saving into four per cent. Top up at two-thirds. It takes ten seconds, it uses the whole jug, and it means the room never goes quiet while a delivery is in transit.

And do not buy a refill for a scent you are not sure about. A refill is a commitment to roughly eight months of one blend in one room, which is a lovely thing when the room is settled and an expensive mistake when it is not. Live with a 50ml for a season first. If you still like it in month three, buy the refill and stop thinking about it until next winter. A portion of every order supports girl-child education through Nanhi Kali.

Frequently asked questions

How many rooms can one 300ml reed diffuser refill keep going?
One room for about eight months, or two rooms for about four months each. 300ml divides into a 130ml bottle 2.3 times — two complete fills plus a 40ml remainder — and a 130ml on six reeds runs 14–18 weeks. It does not stretch to three rooms; that is the 500ml at ₹3,499.
What does a 300ml refill work out at per millilitre?
₹8.00. ₹2,399 ÷ 300 = ₹8.00 a millilitre, against ₹9.61 for a new 130ml bottle at ₹1,249. So each fill costs ₹1,040 rather than ₹1,249 — a saving of ₹209, or about seventeen per cent, on the basis that the glass, collar and reeds were always the durable part.
What should I do with the last 40ml of a 300ml refill?
Plan for it, because it is ₹320 of liquid. The best method is to top the bottle up at about two-thirds down rather than waiting for empty, so the jug goes in across three visits. Failing that, keep a small bathroom bottle in the same scent — 40ml on two reeds runs about nine weeks. Wasted, it drops your saving from seventeen per cent to four.
Is the 500ml refill better value than the 300ml?
Per millilitre, yes: ₹3,499 ÷ 500 = ₹7.00 against ₹8.00. It also divides more neatly into 130ml bottles — 3.85 times, so three complete fills with 110ml over rather than two fills and 40ml. It is the right size for a house running three bottles of one scent, and the wrong size for a house running one.
Does a refilled bottle smell weaker than a new one?
The liquid is identical. What changes is the reeds: fibre clogs as heavier fragrance molecules saturate the core, wicking slows, and throw falls off after a few months. Fit fresh reeds every time you refill and the bottle performs as it did when new. Keep the same reed count you were running rather than adding more.
Refills, divided honestly
2.3 fills — one room for eight months, or two for four
A 300ml SOSA reed diffuser refill at ₹2,399 is ₹8.00 a millilitre against ₹9.61 in a new 130ml bottle, and fills that bottle twice with 40ml over. The 500ml at ₹3,499 is ₹7.00 a millilitre and fills it three times. Oil-based, composed and made in Pune, phthalate-free. Fit fresh reeds every time you refill. A portion of every order supports girl-child education through Nanhi Kali.
Shop SOSA reed diffusers → See the Sukoon ₹1,899
Continue the read
More on how much you actually need
Editorial standards & sources
About this guide: Written by Sonal Sahani, ISIPCA Versailles-trained founder and perfumer at SOSA Home & Body, on sizing home fragrance to a home. Coverage and longevity figures are SOSA's own for the stated products, measured on six reeds in a closed room of standard ceiling height; real rooms with draughts, heat or high ceilings will differ. Prices are current at the time of writing.

SOSA products & prices (verified August 2026): Hotel Collection water-based ultrasonic diffuser fragrance 15ml ₹299 · 100ml ₹999 · 300ml ₹1,799 · Pack of 7 (15ml, all fragrances) ₹1,799; refills 100ml 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). Diffusers: Boond 300ml ₹899 · Sukoon 500ml ₹1,899 · Megh 6L ₹3,499. Water-based, phthalate-free, composed to IFRA standards for home diffusion; 3–6 drops per tank. Made in India, Pune. The Hotel Collection scents are SOSA's own interpretations inspired by the world's finest hotels; all hotel names are trademarks of their respective owners and are used only to describe the scent style — SOSA is an independent Indian fragrance house, not affiliated with or endorsed by any hotel brand. Prices and availability subject to change — see the live product pages.
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