How Do I Calculate Fragrance Oil and Base Quantities for 100 Reed Diffuser Bottles of 120 ml Each While Accounting for Density and Filling Losses?

The numbers, before any explanation

Here is the full calculation for the order in your question: one hundred bottles, each holding 120 ml of finished diffuser liquid, made with fragrance oil at 20% of the blend by weight — the load CSI's base pages recommend as a working point inside their 10–30% range. The first step is to turn 12,000 ml of finished liquid into grams. CSI publishes no density for any of its bases or oils, so this page uses a labelled example density of 1.00 g per ml and shows exactly how far the answer moves at ±5%. At 1.00 g/ml, each bottle holds 120 g of blend: 24 g of fragrance oil and 96 g of base. One hundred of them is 12,000 g net — 2,400 g of oil and 9,600 g of base.

That net figure is what ends up in the bottles. It is not what you buy. Some liquid stays in the mixing vessel, on the stirrer and in the jug or funnel; some goes into the retained samples you should keep from every batch; and glass breaks. This page uses three labelled working assumptions you replace with your own: two bottles' worth of liquid kept as retained samples, a 3% transfer loss applied to liquid only, and two spare bottles for breakage applied to glass only. Applied in that order, the liquid you need to make is 12,607.2 g: 2,521.4 g of oil and 10,085.8 g of base. Rounded to listed CSI packs, that is 21 × 500 ml of base and 2 × 1 kg + 1 × 500 g + 2 × 15 g of oil.

Read the table from left to right and two things stand out. First, when the blend and the base share the same density, the number of 500 ml base packs does not change — 21 in every case — because 80% of the blend by weight is also 80% by volume; only the grams of oil move, from 2,395 g to 2,648 g. Second, when the oil and base differ in density, as they usually do, the blend density shifts and so does the base volume. In the mixed example (oil 0.95, base 1.05 g/ml, both labelled examples), the blend comes out at 1.028 g/ml and the base volume drops to 9,878 ml, which still rounds to 20 packs. The cost spread across all four scenarios is ₹35,570.00 to ₹36,999.00 for oil and base. That spread is what measuring your density in a pilot protects you from.

The calculation, step by step, so you can rerun it

The section pillar, how much fragrance oil to add to 100 ml of reed diffuser base, explains why fragrance load is a share of the total blend and not a share of the base; this page assumes that convention and takes it to a production order. Calculating a 120 ml diffuser at 20% by weight is the single-bottle version of this calculation and is worth reading first if the per-bottle grams are new to you. What follows is the same arithmetic scaled to a hundred, with every allowance in the order it should be applied.

Filling losses: where the extra liquid actually goes

The difference between a calculation that works and one that leaves you three bottles short is usually not the arithmetic but the allowance stack. There are four separate things to account for in a reed diffuser order, and they do not behave the same way. Some are whole units, some are percentages, some apply to liquid and some to glass. Mixing them up is how makers either run short on the last tray or buy two extra bottles of base they will not use for months.

Transfer loss depends almost entirely on your equipment. A single wide vessel poured through one funnel loses less than three small beakers decanted into a jug; a viscous blend clings more than a thin one. The 3% on this page is a placeholder. In the pilot, weigh the empty vessel, weigh the mixed blend, weigh every filled bottle, and subtract: whatever is missing is your loss. Then use that figure in the production calculation. If it comes out at 1%, you have saved most of a 500 ml bottle; if it comes out at 6%, you will be glad you measured before ordering for a hundred.

Reeds are a different case. When a customer puts reeds into a full bottle, the reeds soak up some liquid and displace more, which is consumption and fill-line behaviour, not a filling loss — do not add it to the transfer allowance. What reed insertion does affect is the fill you can safely promise, which is why the pilot tests two fill levels. How many fibre reeds to test in a 100 ml bottle covers reed count in depth, and a 120 ml diffuser that lasts only three weeks covers what happens to consumption once the reeds are in.

The ten-bottle pilot that makes the big order safe

Before spending ₹54,394.04 on the full order, spend ₹6,360.00 on a pilot that answers the four questions the calculation cannot: what your blend actually weighs per millilitre, whether 120 ml plus reeds fits the bottle comfortably, what your real transfer loss is, and whether the blend stays clear through its rest and a 7-day hold. It uses one pack of ten Gold 120 ml bottles, one 500 ml bottle of Lift Base, and the smallest packs of Lemongrass and Lime that cover 239.0 g of oil. One variable changes between arms: the fill volume. Everything else — base lot, oil lot, load, reeds, room — is identical.

Three things come out of the pilot that the full order needs: a measured density, a measured transfer loss, and a fill volume you can promise without overflow. If arm A overflows or leaves almost no headspace, a 110 ml fill is the practical promise; at 110 ml per bottle the full production run needs ₹33,167.52 of oil and base instead of ₹36,312.04, a saving of ₹3,144.52. If arm B's room score and grams per day match arm A's over the week, you have learned that the lower fill costs you nothing visible in the room in that time. The full life of the bottle is a longer test — the 30-day performance test sets that out.

The priced production order, and what to buy now versus later

Everything below uses listed, in-stock CSI packs. Base comes only in 100 g (Pure Performance) and 500 ml, so a production base order is a count of 500 ml bottles; there is no 1 kg, 5 kg or 25 kg base listing, and larger quantities are quoted on WhatsApp with no published volume discount. Oils come in 15 g to 1 kg packs; for most oils the 1 kg is not meaningfully cheaper per gram than the 100 g, so the larger packs buy convenience and stock security rather than a lower rate. Lemongrass and Lime is one of the exceptions: its 1 kg costs ₹5.20 per gram against ₹5.90 at 100 g.

At production rates, each finished bottle carries ₹124.80 of oil (at the 1 kg rate), ₹211.01 of base (at 1.00 g/ml example density), ₹106.20 of glass and ₹64.00 of reeds at ₹8.00 each — ₹506.01 in CSI materials, before labels, boxes, courier, labour and GST. The order total divided by a hundred is a little higher, ₹543.94, because it carries the retained samples, the transfer loss, the spare bottles and the unused part of the last packs. Calculating raw-material cost per 120 ml bottle at 22% breaks the per-bottle cost down further and shows how it moves with the oil you choose.

The decision rule: order now, adjust, or wait

Apply this after the pilot. Stop at the first line that is true. The rule is written so that a partner or an employee reading the same batch sheet would place the same order.

If you are planning more than one fragrance for the same hundred bottles, each oil needs its own density measurement and its own clarity hold; a blend at 20% in one oil can weigh differently from the same 20% in another. Standardising load versus optimising each SKU covers running different oils at different loads, how many 100 ml bottles 1 kg of finished liquid fills covers the density question from the other direction, and scaling a 100 g trial to a 10 kg batch covers mixing a hundred bottles in one go without the ratio drifting.

The CSI products in this order

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