How Much Fragrance Oil Should I Add to 100 ml of Reed Diffuser Base if I Want a Strong-Smelling Finished Product?

The number: what to add to 100 ml of base

Every CSI reed-diffuser base page expresses fragrance load as a share of the total blend — the base and the oil together. The Pure Performance Base page says to start at 10%, recommends 20%, calls 75% base + 25% fragrance its "typical working blend" and sets 30% as the maximum. The Longevity Base, Lift Base, Depth Base and Softness Base pages all give the same 10–30% range. So when you ask how much oil to add to 100 ml of base, the honest answer depends on which number you want the finished liquid to carry, and it is always a little more oil than the percentage itself suggests, because the oil you add becomes part of the total.

The formula that turns a fixed quantity of base into a true load is simple: oil = base × L ÷ (1 − L). With 100 g of base, a true 20% needs 25.00 g of oil and gives 125.00 g of finished blend, of which 25.00 g is exactly 20%. A true 25% needs 33.33 g; the page's 30% ceiling needs 42.86 g. If your base weighs 1.00 g per ml — an example figure; CSI publishes no density for any base — then 100 ml of base is 100 g and these grams also read as millilitres. Your base will not weigh exactly that, which is why the rest of this page asks you to weigh.

So for a strong-smelling finished product, the working answer is: start your development at the page's recommended 20% (25.00 g of oil per 100 g of base), bracket it with 25% (33.33 g) and 30% (42.86 g), and choose the lowest of the three that reaches the strength you set as your house target in a real room, stays clear for seven days, and keeps the reeds clean. Never go above 30%, and never above the oil's own IFRA Category 10A limit if that is lower — the lower of the two always wins. That last condition is not a formality; it is the reason the maximum-percentage post exists.

This page is the pillar for the whole fragrance-percentage section of the series. It answers the 100 ml question in depth, explains why "strong" is a room result rather than a bottle result, prices a three-load test, and ends with a question-finder for the nineteen posts that take each part further. If you are still choosing a base, which reed diffuser base to buy in India is the pillar for that decision; if you have never made a diffuser, how to make a 100 ml reed diffuser with fragrance oil and a ready-made base walks the full make first.

Two conventions, one mistake that costs you strength

There are two ways people talk about diffuser loads, and they give different liquids. The first is the one CSI's pages use: the load is the oil's share of the total blend. The second, common in forums and in handwritten recipes, is the oil added "as a percentage of the base": 20 ml of oil for every 100 ml of base. Both are internally consistent. The trouble starts when a recipe written in one convention is followed in the other, because the answer to "is my diffuser at 20%?" changes.

Take the most common case. A maker reads "20% recommended" on the page, measures 100 ml of base, and adds 20 ml of oil. The finished liquid is 120 ml, and the oil is 20 ÷ 120 = 16.67% of it. They believe they made a 20% diffuser; they made a 16.67% one. At the page's 30% ceiling the gap is wider: 30 ml on 100 ml is 23.08% of the finished blend. If that maker then writes "my diffuser is weak at 20%, so I will go to 30%", they are really stepping from 16.67% to 23.08% — and comparing their result with someone who weighed a true 20% is meaningless.

The third row is the one we recommend for development work. Instead of fixing the base and calculating the oil, fix the finished quantity — say 100 g of blend for one bottle — and split it: oil = 100 × L, base = 100 × (1 − L). Every bottle in a comparison then holds the same mass of liquid, which matters when you start weighing bottles to see how fast they lose liquid. With the base fixed and the oil added on top, a 30% bottle holds 142.86 g and a 20% bottle 125 g, and the heavier one will look as if it lasts longer simply because it started fuller. The 120 ml weighing sheet shows the fixed-total method step by step, and the weight-versus-volume post explains why it keeps batches consistent.

Why you should weigh, and what density does to your answer

The Pure Performance page's own worked example is by volume: "for a 100 ml finished diffuser at 25%: 75 ml base + 25 ml fragrance oil". That is a clear way to explain a ratio, but it quietly assumes the oil and the base have the same density. They usually do not, and CSI publishes no density for any base or any oil. Fragrance oils vary widely from one to the next, so 25 ml of one oil can weigh noticeably more or less than 25 ml of another. If you measure by volume, the load you actually made depends on densities nobody has told you.

Weighing removes the guess. A load by weight is the same load whatever the densities are, because the grams are what you put in. You need only one density figure, and only if you must convert a bottle's millilitres into grams to decide how much blend to make: weigh 100 ml of your own finished blend in a beaker on a scale, once, and write it on the recipe card. Until you have done that, every conversion on this page uses an example of 1.00 g per ml and shows what happens if your real figure is 5% lower or higher.

A ±5% density difference moves a 20% blend by less than one percentage point either way — 20.83% to 19.23%. That is small next to the 3.33-point error from the convention mistake, but it is not nothing when you are trying to tell 20% from 22% apart in a three-load comparison. It also matters for buying: a 500 ml bottle of base holds 475 g at 0.95 g/ml and 525 g at 1.05 g/ml, so the number of bottles you can fill from it changes with the density you have not yet measured. That is why every purchase quantity on this page is sized at the low end of the band — so you never run short. The density and fill-count post takes this all the way to how many 100 ml bottles one kilogram of finished liquid fills.

What "strong" means for a reed diffuser — and why the bottle lies

Open a freshly mixed 30% blend and it will almost always smell stronger than a 20% one at the neck of the bottle. That tells you very little about how the finished diffuser will fragrance a room. A reed diffuser has no heat and no fan. The liquid travels up the fibre reeds by capillary action, spreads across the exposed reed surface, and the fragrance leaves the reed surface by evaporation into still room air. What a person notices across the room depends on how fast the fragrance components leave the reeds, how much reed surface is wet and exposed, how big and how ventilated the room is, its temperature, and how quickly the nose adapts.

Load is one input to that chain, not the whole of it. A higher load commonly puts more fragrance into every gram that the reeds lift — but heavy, viscous oils at high loads are also commonly described as slowing how quickly liquid travels up the reeds, and a base designed for slower diffusion will deliver its fragrance over more days at a lower rate. That is why the right question is never "which load is strongest in the bottle?" but "which load gives my house strength target in my test room, for long enough, at a cost I can sell?". Does adding more oil always make a diffuser stronger? goes into the capillary side of this, and the hub for weak diffusers covers the room side when a finished product disappoints.

There is no industry standard room, distance or score for diffuser strength — no "ml per square foot" rule exists. The table is an example of a house standard: yours to set once, write down and keep. What matters is that your 20%, 25% and 30% bottles are judged in the same room, in the same way, on the same days. A diffuser that scores well in a closed, air-conditioned bedroom may score lower in a ventilated living room; the room-size and airflow post deals with that difference directly.

The three caps on your percentage — the lowest one wins

Wanting a strong product pushes the load up. Three separate limits push back, and your working ceiling is whichever is lowest for the specific oil and base you are using.

Reed diffusers are listed under IFRA Category 10A in current IFRA amendments, as suppliers' IFRA guides commonly summarise it — confirm against the category descriptions printed on the certificate itself. The certificate gives the maximum concentration of that oil in the finished product for each category. Because your finished product is the blend, the load you choose must not exceed the certificate's Category 10A figure. If the certificate says a lower figure than 30%, that lower figure is your ceiling for that oil, whatever the base page allows. We do not publish an IFRA percentage for any oil, and we will not guess one here — ask for the certificate. Determining the maximum appropriate percentage walks through reading a certificate, and the post on a certificate lower than 25% covers the case where the limit and your target clash.

Which CSI base for which fragrance family

The load question cannot be fully separated from the base question, because CSI's five in-stock bases are written for different fragrance families, and the Longevity page explicitly says heavy oils such as oud "can cloud at maximum load in some bases". What follows is what each page says it is for. These are the pages' own descriptions, quoted as claims to test; we publish no throw or longevity data for any base, and we never rank one above another.

For a first strength test, Pure Performance Base has two practical advantages. It is the only base with a 100 g size, so a small first trial costs ₹325.00 rather than ₹1,099.00, and its page is the one that spells out the 20% recommendation and the 25% typical blend you are about to test. Note one subtlety when comparing its two sizes: 100 g at ₹325.00 is ₹3.25 per gram, while 500 ml at ₹1,099.00 is ₹2.20 per millilitre — different units. The 500 ml is cheaper per gram for any base density above 0.676 g/ml (₹1,099.00 ÷ 500 ml ÷ ₹3.25 per g), which almost certainly covers your base; weigh 100 ml to confirm. For families the other pages name, test the family base as a second arm once your load is close. The full base decision belongs to the which-base pillar; the DPG, Augeo-type and alcohol comparison covers carriers CSI does not sell.

The three-load test for a strong product

The example below uses Pure Performance Base and Blue Ocean in ten 120 ml Gold Reed Diffuser Bottles, each filled with 100 g of finished blend — a labelled example fill that leaves headroom for reeds. Use your own oil if you have chosen it; Blue Ocean is here because the arithmetic needs one and the Pure Performance page says it suits every family. Three bottles per load is a working practice for a screen, not a verdict. The tenth bottle holds plain base with reeds: it shows how much weight the base alone loses and whether the base itself has a smell you can detect in the room.

In this design the room scoring has one practical problem: you cannot put nine diffusers in one room and score them separately. Score them one at a time — each bottle carried into the test room for a fixed period (for example 60 minutes) with a 30-minute empty-room gap and a window opened between bottles, or rotate bottles through two or three identical rooms. Code each bottle with a letter so evaluators do not know its load. Comparing 18%, 20% and 22% uses the same idea to compare narrower steps, and the 30-day test post sets out a full month-long protocol.

Four measurements that decide it

Every test in this series uses the same four measurements, so results from different posts and different rounds can be compared. None of them needs a laboratory.

Weight loss is the measurement makers skip and the one that explains most results. If a 30% bottle scores no higher than a 20% bottle in the room and also loses weight more slowly, the higher load may be slowing the liquid on the reeds rather than helping — the pattern the 25%-but-barely-smells post investigates. If it scores higher and loses weight at a similar rate, the extra oil is doing its job. The days-of-life projection is simple: fill grams ÷ grams lost per day. With an example loss of 2.0 g a day — a figure to show the arithmetic, not a measurement of any base or oil — a 100 g fill lasts 50 days. Your weighed figure replaces it.

Notice that 5 is a failure, not a win. A diffuser for a bedroom or a small apartment that overwhelms the room is a returned product; strong without becoming overpowering deals with that ceiling. A sensible house target for a "strong" product might be 3 or 4 at 2 m on day 7 and still 3 on day 30 — your call, written down before the first score.

What a stronger load costs per bottle and per day

Every point of load swaps base for oil, and oil usually costs more per gram. With Blue Ocean at its 1 kg rate (₹4.96 per g) and Pure Performance Base bought in 500 ml at an example 1.00 g/ml (₹2.20 per g), the liquid in a 100 g fill costs:

Going from 20% to 30% adds ₹27.58 of liquid cost to each 100 g bottle with this oil and base. The bottle (₹106.20 each in a pack of ten) and six black reeds (₹8.00 each from the 50-pack) add ₹154.20 whatever the load, so the bottle and reeds are a large share of the total — the extra oil is a smaller share than many makers expect. Cost per day is the figure a customer actually buys: at the example 2.0 g/day, the liquid costs ₹5.50 a day at 20%, ₹5.78 at 25% and ₹6.05 at 30%. If the higher load changes the g/day you weigh, the per-day figure changes with it — which is why the most economical percentage post compares loads by cost per day of measured life, not cost per bottle.

These figures exclude labels, boxes, freight, labour and GST, and they use the 1 kg oil rate. For Blue Ocean the 100 g rate is ₹4.95 per g, so for this oil buying 1 kg mostly buys stock security rather than a lower rate — per-gram breaks above 100 g are rare across CSI's range. The 22% cost-per-bottle post runs a full raw-material costing for one SKU; what a 100 ml diffuser costs to make does it for the business section.

The priced test kit

Priced with listed, in-stock CSI sizes. Oil and base include a 3% transfer-loss working allowance for liquid left on vessel walls. Base is sized at the low end of the density band (0.95 g/ml) so the kit never runs short: at that density two 500 ml bottles hold 950 g against a need of 798.25 g. If you have already weighed your base at 1.00 g/ml or above, one 500 ml plus three 100 g packs (₹2,074.00) also covers it.

The oil line looks large because each arm needs real liquid: arm A uses 60 g of oil, arm B 75 g, arm C 90 g. If budget is tight, run two bottles per arm instead of three and drop the blank — but keep the 20% control. For a cheaper screen in smaller bottles, the 50 ml Gold bottle is ₹82.60 each; choosing between 15%, 20% and 25% prices exactly that. For a stronger room effect you can also test reed count before load — the reed page says more reeds give "stronger throw and faster diffusion", a page claim the reed-count post tests.

The decision rule: which load to bottle

Apply after the day-7 read and again after day 30. Stop at the first line that is true.

Note how often the rule stops short of the 30% ceiling. That is deliberate. The cheapest strength you will ever buy is the one that comes from the right reeds, the right room placement and the right base for the family — not from oil you add past the point it helps. When no arm reaches your target, the weak-at-15% post and the systematic weak-diffuser capstone work through the other variables in order.

From the test bottle to a production batch

Once a load passes, write the formula as a share of the total by weight and scale it by multiplying, never by adding. A 25% formula for one 100 g bottle is 25.00 g oil + 75.00 g base; for a 500 g batch it is 125.00 g + 375.00 g; for 5 kg, 1,250 g + 3,750 g. The percentage does not change, so the formula does not drift. The 500 g trial batch post splits a batch into bottles with a loss allowance, the 100 g to 10 kg post covers mixing larger volumes, and the 100-bottle post turns a production run into an order that does not run short.

One caution on buying for production: CSI lists bases only in 100 g (Pure Performance) and 500 ml sizes. There is no listed 1 kg, 5 kg or 25 kg base. For larger quantities, message us on WhatsApp for a quote; no volume discount is published, and we will not quote one here. Oils are listed up to 1 kg per pack. 1 kg, 5 kg or 25 kg of base and the section capstone on scaling to 25 kg deal with those quantities.

The CSI products in this test

Find your exact percentage or formula question

This page is the hub of the series' fragrance-percentage section — "Fragrance oil percentages and formula calculations". Every post below uses the same convention (load = share of the total blend, by weight), the same four measurements and the same idea of a written house standard; each starts from a different question.

Four more sections pick up where this one stops. Starting out: raw materials and the first base is the hub for makers who have not yet made a diffuser. Which reed diffuser base to buy is the hub and pillar for choosing a carrier, with the DPG, Augeo-type and alcohol comparison as its second pillar. Weak, fast or clogged diffusers is the troubleshooting hub. Costs, bulk buying and starting a business is the business hub, ending in the full business pillar.

Frequently asked questions