How Do I Make a Reed Diffuser with 22% Fragrance Oil and Calculate the Raw-Material Cost per 120 ml Bottle?

Making it: 22% by weight, bottle by bottle and batch by batch

A 22% reed diffuser is one in which fragrance oil is 22% of the finished liquid's weight and base is the other 78%. That sits inside the 10–30% range every CSI base page gives and a little above the 20% that the Pure Performance page recommends as a working point. Before you can cost a bottle, you need two figures CSI cannot give you: how much liquid goes in it, and what that liquid weighs. The Gold Reed Diffuser Bottle's 120 ml is the listing's size, not a published fill line, and reeds displace liquid, so this page costs a labelled example fill of 110 ml and shows 100 ml and 120 ml alongside. No density is published for any CSI base or oil, so this page uses an example 1.00 g/ml and shows ±5%.

At those figures one bottle holds 110 g of blend: 24.2 g of fragrance oil and 85.8 g of base. Weighing that for every bottle is slow and invites small errors, so mix in batches. Ten bottles — one pack of Gold bottles — with a 3% working allowance for what stays in the vessel is 1,133.0 g of blend: 249.3 g of oil and 883.7 g of base, weighed onto a tared vessel, stirred until uniform, and rested 24–48 hours as the base pages ask before you fill by weight. Calculating a 120 ml diffuser at 20% by weight walks through the per-bottle weighing in detail, and why weight beats volume explains why the batch sheet should never say millilitres.

The raw-material cost per 120 ml bottle

The cost formula is the one used throughout the series: liquid cost = fill grams × (load × oil ₹ per g + (1 − load) × base ₹ per g), plus the bottle and the reeds. Base is sold by the 500 ml, so its rupees per gram need the density: Longevity Base at ₹1,296.00 for 500 ml is ₹2.59 per ml, which is ₹2.59 per gram at the example 1.00 g/ml. Bergamot Amber costs ₹5.60 per gram at the 100 g pack — the size a small workshop is most likely to buy for a run of ten to twenty bottles.

Two things surprise most makers when they see this table. First, at 22% the base, not the fragrance oil, is the larger liquid line: ₹222.39 against ₹135.52, because 78% of the blend is base and Longevity is ₹2.59 a gram at the example density, while this oil is ₹5.60 a gram for only 22% of it. A cheaper oil makes the gap wider; a dearer one closes it. Second, the bottle and reeds together are 32.1% of the total. Saving a few grams of oil moves the bottle cost far less than the choice of reed colour or pack size. The total excludes labels, a box, a reed sleeve or stopper (CSI does not list these), courier, labour and GST — add your own quotes as labelled lines.

What moves the cost, one line at a time

The diagram above shows six single changes against the base case. Each table below takes one of them in more detail, so you can see which decisions are worth agonising over and which are not.

For this oil the real price step is between the 15 g and the 50 g: the 50 g and 100 g are the same ₹5.60 per gram, and the 500 g and 1 kg are ₹5.44 and ₹5.44 — a saving of under ₹3.95 a bottle. That pattern is typical on CSI's catalogue: per-gram breaks above 100 g are rare, and buying bigger mostly buys convenience and stock security rather than a lower rate. Volume pricing beyond the listed packs is quoted on WhatsApp and no discount figure is published.

Density changes the liquid cost less than you might expect, because a heavier blend means more grams of both oil and base in the same 110 ml, but the base is priced per millilitre, so its line barely moves; the oil line moves by about 5%. Fill matters more: going from 110 ml to 120 ml adds ₹32.54 a bottle. And the load — the number most makers argue about — moves the bottle by ₹6.62 between 20% and 22%, and by ₹9.93 between 22% and 25%, with this oil. Comparing 18%, 20% and 22% by room throw, consumption and cost per day is where to decide whether 22% earns that money back in performance.

Oil choice is the one lever that can move a 22% bottle by a large amount. From British Rose in Softness to Santal Noir in Longevity, the bottle cost spans ₹440.60 to ₹613.99. That is a range set by the oils' listed prices, not by any claim about how they perform — CSI publishes no diffuser throw or longevity data for any oil. Choose the fragrance your customer wants; then cost it honestly.

Before you price it: a 22% compatibility check

Costing a formula that clouds or separates is wasted arithmetic, so check that 22% holds in your base with your oil before you put a price on it. The Longevity page itself warns that "heavy oils like oud can cloud at maximum load in some bases" and says to reduce the percentage and retest if clouding occurs. A one-variable check against a 20% control — the load the Pure Performance page recommends as a working point — answers the question in a week, using one pack of Gold 120 ml bottles.

The capped bottles are the clarity test: any haze, layering, droplets or sediment at 24–48 hours or 7 days, against a white card and a black card, means the formula is not stable at that load in that base. A cool-room night is a useful extra check — record the temperature, it is a labelled example condition, not a specification. The reeded bottles give you grams per day (weight lost ÷ days, reeds in) and a blind room score on your house scale. If the 22% bottles stay clear, lose weight at a similar rate and score above the 20% control, the extra ₹6.62 a bottle is buying something. If they score the same, the 20% formula is the honest product. Can I increase from 20% to 30%? covers the higher end of the range, and does more oil always mean a stronger diffuser? covers why it often does not.

The decision rule

For a whole-range view rather than one SKU, the most economical fragrance percentage compares loads by cost per day of use, standardising load or optimising each SKU covers different oils at different loads, and what a 100 ml diffuser costs to make in India gives the 100 ml version of this table.

The CSI products in this bottle

Frequently asked questions