The calculation, from the convention up

Three steps, one division, and one denominator that has to be right.

Start with the bottle rather than the pack. A finished 100 g bottle at a 20% load is 20 g of oil and 80 g of base, because CSI's base pages state load as a percentage of the total finished blend. The oil is part of the 100 g, not an addition to it. Get that one sentence right and the rest of this page is arithmetic; get it wrong and every pack count you calculate for the rest of your life is wrong in the same direction.

Then the pack. A 500 ml pack of base is 500 g of base for the purposes of this calculation, which is how every figure on this page treats it. Divide the pack by the base in one bottle: 500 g divided by 80 g is 6.25 bottles. That is 6 whole bottles, with the remaining quarter of a bottle's worth of base still in the pack and still yours - it goes into the next batch, or into a trial arm, or it sits in the jar.

Then the batch. Multiply the base in a bottle by the number of bottles, divide by 500 g, and round up to a whole pack, because you cannot buy a part pack. Fifty bottles at 20% need 4,000 g of base, which is exactly eight packs; a hundred need 8,000 g, which is exactly sixteen. Both of those come out without a remainder, which sounds convenient and is actually a warning - there is no slack in either order, so a spill or an overfilled bottle costs a whole extra pack.

That is the whole method, and it works for any bottle size. A 120 g fill - the weight most makers put into a 120 ml bottle - takes 96 g of base at 20%, so one pack fills 5.21 of them, or 5 whole ones. A 50 g fill takes 40 g and one pack fills 12.5, which is 12 whole bottles. Same division, different denominator - and the denominator is the base in one bottle at the rung you established in your own testing.

Two habits make the method reliable rather than theoretical. Weigh, do not measure by eye or by the markings on a jug: a 0.1 g scale costs less than a single 500 ml pack and it is the instrument the whole calculation rests on. And write the fill weight down as a number you have actually weighed, because a 100 g bottle is a decision rather than a fact - the same 120 ml glass can take a 100 g fill or a 120 g one, and those two fills yield 6.25 and 5.21 bottles from the same pack. A maker who assumes the fill and calculates the pack count exactly will be short of base on the first batch.

The convention, the wrong denominator, and whose band this is

Two sentences to fix before any multiplication: how load is stated, and what the published band is a band for.

CSI's reed and car diffuser base pages publish fragrance load as a percentage of the total finished blend: 10% as a starting point, 20% as the recommended working load and 30% as the maximum, with 75% base plus 25% fragrance oil given as the typical working blend and a worked example that reads - for a 100 ml finished diffuser at 25% fragrance, use 75 ml of base and 25 ml of fragrance oil. Longevity publishes a slightly higher working band of its own: “The recommended working ratio is 70-75% Longevity Base with 25-30% fragrance oil.”.

The candle convention is the opposite, and most Indian diffuser makers came through candles, where load is a percentage of the wax weight. So the commonest arithmetic error in this trade is dividing the oil by the base. 25 g of oil with 75 g of base is 25% of the total finished blend and 33.33% of the base weight. Both are arithmetically fine; only the first can be compared with a published rung, quoted to a supplier, or used in the division on this page. If your records are in the second form, convert them before you order - 20 g of oil into 100 g of base is a 120 g blend at 16.67%.

Now the second sentence, and it is the one that makes this series different from its fragrance-oil siblings. Every published figure in the diffuser range - the 10/20/30% band, the typical working blend, the clarity step, the 24-48 hours rest before bottling - is written about fragrance oil. Nothing in the CSI catalogue publishes a load, a dose, a compatibility statement, a flash point, an SDS or a shelf life for any essential oil in a diffuser. So when this page calculates at 20%, it is calculating at a rung you chose inside the only published bracket that exists, not at a dose anyone published for your oil.

That does not weaken the arithmetic at all, and it is worth being clear why. The division does not care what is in the bottle: if your established rung is 14% because that is where your lavender blend stays clear, then a 100 g bottle holds 14 g of oil and 86 g of base and one pack fills 500 g divided by 86 of them. What the absence of a published load changes is only the authority of the rung - which is yours, established on your bench, after the published rest, and worth writing down with its date and its grams.

The yield table: every rung, and the fills you actually sell

Three bottle sizes, one pack, and the figure you will actually quote.

The 100 g fill is the one in the title and the one most Indian makers price around, because it goes comfortably into a 120 ml bottle and leaves headroom at the neck. At 20% it yields 6.25 bottles a pack. The 120 g fill - the same bottle filled fuller - takes 96 g of base and yields 5.21, or 5 whole bottles. The 50 g fill, which is the gifting and sampler size, takes 40 g and yields 12.5 - 12 whole bottles from one pack.

Read the whole-bottle column rather than the decimal when you are ordering, and read the decimal when you are costing. They answer different questions. 6.25 is what a pack is worth to you in base; 6 is how many finished bottles come out of it before you open the next pack. The quarter bottle in between is not waste - it joins the next pack's worth - but it is not a bottle either, and a maker who orders on the decimal ends up one bottle short on every pack.

The bases differ in price but not in this arithmetic. Four of the five 500 ml packs are the same ₹1,099.00 - Pure Performance, Depth, Lift and Softness - and Longevity is ₹1,296.00, ₹197.00 more for the same 500 ml. The yield is identical: a Longevity pack fills 6.25 bottles of 100 g at 20% exactly as the others do, because the division is on grams and not on rupees. What changes is the cost per bottle, which is ₹259.20 per 100 g of base against ₹219.80.

One size that is not in this table on purpose: the 100 g trial pack. It fills bottles too, at a fifth of the rate of a 500 ml pack, but it is priced for testing - ₹3,250.00 a kilogram against ₹2,198.00, which is 47.86% dearer per gram, or ₹325.00 per 100 g against ₹219.80. Use it to establish the rung this calculation needs, then do the calculation at the 500 ml rate. A production yield computed at the trial pack price overstates your costs by that same 47.86%.

One more reason to keep the fill weight explicit: it is the lever that changes your yield most, and it is entirely yours. Moving from a 120 g fill to a 100 g fill in the same 120 ml bottle takes the pack from 5.21 bottles to 6.25 at the same rung - a fifth more product out of the same base - and the customer's bottle still looks full because the headroom at the neck is part of the design. That is a legitimate product decision rather than a trick, as long as the fill weight is what your label says and your pricing is built on the weight you actually put in.

The leg most makers miss: lower load, fewer bottles

Step the load down to clear a haze and your base order goes up. Both legs are real.

This is the single most useful consequence of the published convention, and it catches almost everybody once. Because load is a percentage of the total finished blend, a lower rung does not just mean less oil - it means more base. At 20% a 100 g bottle holds 80 g of base; at the published 10% rung it holds 90 g. So the same 500 ml pack falls from 6.25 bottles to 5.56, which is 0.69 bottles fewer, and the 20% rung yields 1.12 times as many bottles per pack as the 10% one.

That matters most at exactly the moment a maker is least likely to think about it: after a trial has come back hazy at the rung they wanted, and the published advice - Lift's “If clouding occurs, the fragrance oil may not be fully compatible at that load - reduce fragrance percentage and retest.” - has sent them down a rung. The formula is fixed, the relief is real, and the base order quietly grows. A maker who had budgeted eight packs for fifty bottles now needs nine, and the ninth pack arrives as a surprise in a spreadsheet that was only tracking the oil.

The honest way to present a step-down is therefore two columns and a net. The oil column gives back real money, because the oil is usually the dearer half: dropping from 20% to 10% returns ₹68.44 of lavender essential oil per 100 g bottle. The base column takes some of it back, because the bottle now holds 90 g instead of 80 g: that is ₹21.98 more base per bottle. The net is ₹46.46 per bottle, down 14.86% - and the oil leg is 3.11 times the base leg, which is why the net still points the right way.

Then there is the pack-count leg, which is not proportional and can bite hard. Fifty bottles at 20% is 4,000 g of base, eight packs. At 10% it is 4,500 g, nine packs. The per-bottle cost went down and the number of packs went up, which means a maker ordering to a budget rather than to a bottle count can find the cheaper formula will not fit in the order they planned. Re-run the pack count every time a rung changes. It is one division and it has already surprised people with more than one spreadsheet.

Both legs in rupees, per bottle

The per-bottle figure is the one you price from, so build it out of its two halves.

A 100 g bottle at 20% with lavender essential oil in a 500 ml base at the common price is ₹312.72 of raw material: ₹136.88 of oil and ₹175.84 of base. At 15% it is ₹289.49; at the published 10% rung, ₹266.26; at the typical working blend of 25%, ₹335.95. Those four figures are the whole liquid cost of the product, and they move almost entirely on the oil, because at ₹6,844.00 a kilogram the oil is 3.11 times the base's ₹2,198.00.

Add the hardware and you have a product cost. A 120 ml gold reed diffuser bottle is ₹106.20 out of a ₹1,062.00 pack of ten, and five white fibre reeds are ₹45.00 out of the ₹450.00 pack of fifty. So one finished 120 ml unit filled to 120 g at the 20% rung is ₹526.46, of which ₹375.26 is liquid. A live CSI page works the margin question from a selling price backwards - the page on costing a 120 ml diffuser back from its selling price - and another works the liquid cost from supplier rates - the page on liquid cost from per-kilogram rates. This page stays on the yield.

It is worth seeing the fragrance-oil figure beside the essential-oil one, because the same bottle at the same rung with Lavender Fragrance Oil is ₹283.84 of raw material against ₹312.72. That difference is the oil line in your costing and nothing else - the base, the bottle and the reeds are identical. It is not a quality or safety comparison in either direction, and a maker who prices both versions should price them as two products rather than as a better one and a cheaper one.

Where the oils genuinely differ from the fragrance oils is the pack ladder, and it is good news for a maker sizing an order. Lavender holds ₹6,844.00 a kilogram and Peppermint ₹5,900.00 at every pack size; Lemon at ₹4,484.00, Ylang Ylang at ₹7,316.00 and Marjoram at ₹8,732.00 step once at the 50 g pack and are flat above it. So above the 50 g pack there is no quantity break on any of the five - the best rate among the packs this page quotes is already in your hand - and a maker can buy oil to the batch rather than to a price break.

Knowing which half dominates changes how you think about the rung. At ₹6,844.00 a kilogram for the oil against ₹2,198.00 for the base, the oil is the expensive part of the bottle, so a rung decision is mostly an oil decision - which is why the oil leg of a step-down is 3.11 times the base leg. It also means the five stocked oils do not cost the same to run: a 100 g bottle at the 20% rung is ₹265.52 with lemon and ₹350.48 with marjoram, on identical base, identical bottle and identical reeds. If two of your scents are priced the same on the shelf, their margins are not.

Fifty bottles: the pack count at both rungs

Both pack counts come out exactly. That is a warning, not a convenience.

Fifty 100 g bottles at the 20% rung need 4,000 g of base. Eight 500 ml packs hold 4,000 g - the requirement exactly, with nothing to spare, so a dropped vessel, a spilled jug or fifty bottles each filled a gram heavy means opening a ninth pack or finishing the run at forty-nine bottles. Buy nine and keep the ninth sealed if the run has a deadline. Eight packs at the common price are ₹8,792.00.

The oil side of the same batch is 1,000 g of lavender essential oil. One 1 kg pack holds 1,000 g - again exactly, with nothing to spare, so the same caution applies on the oil as on the base, and the oil is the dearer of the two: ₹6,844.00 for the kilogram. Base and oil together are ₹15,636.00 for the batch, which is ₹312.72 a bottle in liquid.

Now the same fifty bottles at the published 10% rung. The base requirement rises to 4,500 g, which is nine packs holding 4,500 g - exactly again, with nothing to spare, so the ninth pack has no allowance in it either - at ₹9,891.00, so the base bill is ₹1,099.00 higher. The oil requirement falls to 500 g, which one 500 g pack covers exactly, with nothing to spare, at ₹3,422.00 - giving back ₹3,422.00. The batch comes to ₹13,313.00, which is ₹2,323.00 less than the 20% version and 14.86% down, at ₹266.26 a bottle.

So the headline from this section is the sentence this series keeps having to say: the cheaper bottle needs the bigger base order. Fifty bottles get cheaper by ₹2,323.00 and the base order gets a ninth pack. And every one of the four pack counts in this section lands exactly on the requirement with nothing spare, which in a real workshop means you should plan one spare pack of whichever material you are more likely to lose - base if you decant by jug, oil if you weigh small amounts by hand.

The ordering sequence that avoids both failure modes is simple enough to write on the order itself. Calculate the base and the oil separately, round each one up to whole packs, and then ask one question of each: what happens if I lose some. On the base the answer is a ₹1,099.00 pack, which is a tolerable surprise. On the oil at the 20% rung the answer is a 1 kg pack at ₹6,844.00, which is not - so the cheap insurance is a 50 g pack of oil at ₹342.20 alongside the kilogram, rather than a ninth pack of base. That is 1,000 g of requirement protected for the price of a fiftieth of the batch.

A hundred bottles, and the figure for a quotation

Double the bottles, double the packs — and then check the freight, which does not double.

A hundred 100 g bottles at the 20% rung need 8,000 g of base. Sixteen packs hold 8,000 g, exactly, with nothing to spare - ₹17,584.00 of base. The oil is 2,000 g, which two 1 kg packs cover as 2,000 g - exactly, with nothing to spare, so keep a small pack beside them for weighing losses - at ₹13,688.00. The liquid total is ₹31,272.00, or ₹312.72 a bottle, which is the figure to put in a quotation before bottles, reeds, labels, packaging and your time.

At the published 10% rung the same hundred bottles need 9,000 g of base - eighteen packs holding 9,000 g, exactly again with nothing to spare, at ₹19,782.00 - and only 1,000 g of oil, which one 1 kg pack covers. That batch is ₹26,626.00, or ₹266.26 a bottle, so the hundred-bottle order gives back ₹4,646.00 at the lower rung while taking two more packs of base to do it.

The pack count scales exactly with the bottle count here, because the fifty-bottle numbers happened to land on whole packs. Do not generalise from that. Seventy bottles at 20% need 5,600 g of base, which is not a pack boundary at all: twelve packs hold 6,000 g and leave 400 g unused, and that rounding is where small orders quietly lose money. Run the division for your actual batch size rather than scaling a published example, which is the whole reason this page is built as a method rather than a table of answers.

The freight is where a hundred-bottle order behaves differently from a fifty-bottle one, and it behaves counter-intuitively. Sixteen packs are 16 kg packed, which is past the heaviest Standard band, so a single parcel jumps to ₹2,400.00; split into 4 parcels of 4 kg it is ₹1,440.00, saving ₹960.00. Eighteen packs are 18 kg: ₹2,400.00 as one parcel, ₹1,600.00 as 2 parcels of 9 kg, saving ₹800.00. That is a real finding about the published rate card and it is worth checking on every order above five kilograms.

There is one more line worth putting in a quotation and it is not a material at all: the remainder you are carrying. A hundred bottles at the 20% rung consumes the sixteen packs and the two kilograms of oil exactly, with nothing to spare, so the next batch starts from zero opening stock and a single mishap during the run costs a whole pack. A seventy-bottle order, by contrast, leaves 400 g of base sitting in a jar - real stock worth ₹879.20 at the 500 ml pack rate, and worth carrying into the next calculation as opening stock rather than forgetting about.

What a trial takes out of the order before production

If the rung is not settled yet, the ladder comes out of the same packs — and it costs you bottles, not rupees.

Suppose you have not established your rung and you are going to run a ladder first: five arms at 25 g each, from the published start to the published recommended load. That consumes 106.25 g of base and 18.75 g of oil. Taken out of the eight-pack order for fifty bottles, it leaves 3,893.75 g of base - which still fills 48.67 bottles of 100 g at 20%, or 48 whole ones. So the ladder costs you two of the fifty bottles you were planning, which is the honest way to price it.

In rupees the ladder is ₹361.87 of material at the 500 ml pack rate, which is 2.31% of the ₹15,636.00 liquid cost of the batch it is protecting - the batch is 43.21 times the ladder. And it is worth noting that 106.25 g of base is more than a 100 g trial pack holds: the trial pack is short by 6.25 g, so a five-arm ladder at 25 g an arm is a 500 ml-pack job, or a three-arm one is not.

The sequence that wastes least is therefore: run the ladder out of the first pack of your production order, rest it the published 24-48 hours, read it, settle the rung, re-run the division at the rung you settled on, and then order the rest. The alternative - ordering eight packs at a rung you have not proved - is how a maker ends up with the right number of packs for the wrong formula, and base is the one material here for which no page publishes a shelf life.

If you would rather keep the trial off the production order entirely, buy the 100 g trial pack for it: ₹325.00, 0.1 kg packed, ₹80.00 in the lightest published Standard band. It costs 47.86% more per gram than the 500 ml pack, which is the price of a testing size, and it keeps your production packs sealed until the rung is a number rather than an intention.

Shipping the base, and why splitting beats one parcel

The published rate card does not reward consolidation above a point. It punishes it.

A 500 ml base pack is 1 kg on the courier's scale, so the packed weight of an order is simply the pack count. One pack is ₹110.00 at the 1 kg Standard band; the 100 g trial pack is 0.1 kg and travels in the lightest published band at ₹80.00. Up to five kilograms there is nothing to think about. Above that, the arithmetic turns, and the turn is large enough to notice on a small business's margin.

Eight packs are 8 kg. As a single parcel that is ₹800.00; as 2 parcels of 4 kg each it is ₹720.00, saving ₹80.00. Nine packs are 9 kg and one parcel at ₹800.00 is already the cheapest published route at that weight, so there is nothing to split. Sixteen packs are 16 kg, which is past the heaviest Standard band: ₹2,400.00 as one parcel against ₹1,440.00 as 4 parcels of 4 kg, which saves ₹960.00 - the largest gap on this page and the one every scale-up order hits.

Eighteen packs tell the same story: 18 kg, ₹2,400.00 as one parcel, ₹1,600.00 as 2 parcels of 9 kg, saving ₹800.00. So the rule of thumb to carry away is not “consolidate to save” - that is false at several published weights - but “check both”, which takes a minute. And bear in mind that nothing above fifteen kilograms has a Standard rate at all, so an order that crosses that line as one parcel changes service as well as price.

Two notes on scope. First, freight here is quoted for the bases only: the base packs carry a packed weight this calculation can trust, and the oil variants are not quoted for shipping on this page. Second, these are published October 2026 rates for the stated parcel weights, and the cheapest published parcelling is computed rather than assumed - which is the only honest way to say it, because the assumption runs the wrong way more often than makers expect.

Ordering the pack count you calculated

The division is done. Now buy the packs, the oil, the bottles and the reeds in the same order of operations.

Base first, because it is the denominator of everything else. Four of the five 500 ml packs are the same ₹1,099.00 and Longevity is ₹1,296.00; the yield is identical across all of them and only the cost per bottle moves. Buy to the rounded-up pack count, and if your calculation came out exactly - as it does at fifty and a hundred bottles - decide deliberately whether you are adding a spare pack or shortening the batch. The 100 g trial pack at ₹325.00 is for establishing a rung, not for filling bottles.

Oil second, to the batch rather than to a price break, because there is no quantity break above the 50 g pack on any of the five stocked oils. For fifty bottles at 20% that is 1,000 g of lavender essential oil - one 1 kg pack at ₹6,844.00, exactly, with nothing to spare. At the 10% rung it is 500 g, which is the 500 g pack at ₹3,422.00, also exactly. The ladder-sized packs are ₹102.66 for 15 g, ₹342.20 for 50 g and ₹684.40 for 100 g, all at the same ₹6,844.00 a kilogram.

Bottles and reeds third, counted in pieces rather than grams. Gold reed diffuser bottles come ten to a pack: five packs hold 50 bottles, which covers fifty exactly, with nothing to spare - so a chipped neck or a cracked base means a sixth pack or a shorter run - at ₹1,062.00 a pack for the 120 ml or ₹826.00 for the 50 ml. White fibre reeds at five a bottle means 250 reeds for fifty bottles: one pack of 500 holds 500, leaving 250, at ₹4,500.00; three packs of 100 hold 300 and leave 50, at ₹900.00 each. The per-reed rate is the same ₹9.00 from the pack of fifty upwards, so the only question is how many you want in stock.

Then write the whole order down as a calculation rather than a list, because that is what makes the next batch quick. Bottle count, fill weight, rung as a percentage of the total finished blend, base per bottle, bottles per pack, packs rounded up, remainder, oil requirement, oil pack, piece counts, freight as one parcel and as a split. Nine lines. Every one of them recomputes in a minute when the rung changes, and the rung will change the first time an arm comes back hazy.

If the batch is your first, consider halving it rather than halving the rigour. Twenty-five bottles at the 20% rung need 2,000 g of base, which four packs hold as 2,000 g - exactly, with nothing to spare again, so the spare-pack question comes back at every scale. What does not scale down is the trial: the ladder that establishes your rung costs the same 106.25 g of base whether you are making twenty-five bottles or five hundred, which means the smaller the first batch, the larger a share of it the testing becomes. It is 2.31% of a fifty-bottle batch, and proportionally more of a twenty-five bottle one. That is an argument for testing once, carefully, and writing it down, not for testing less.

Frequently asked questions