How to Calculate Fragrance Oil for Any Candle Size

The formula, and the two numbers it needs

Oil grams = wax grams × load. That is the whole calculation, for a 40 g votive or a 25 kg production melt. There is no candle size at which it stops working, no adjustment for jar shape, and nothing to look up once you have the two numbers. What makes fragrance maths go wrong is never the multiplication — it is that people multiply the wrong weight, or apply a percentage that was defined against something else.

The load comes from the pages. On CSI product pages a candle load is always stated as a percentage of total wax weight: Lavender Fragrance Oil states 6–10% of total wax weight, Citrus Lemon states soy 6–10%, and Luxury Soy Wax CSI 464 states a maximum of 10%. Where the wax figure and the oil figure differ, the lower one governs your batch, and that is the number you put into the multiplication.

The wax weight comes from the jar, and it is the part most makers guess at. A 150 g jar takes 150 g of wax, so at 8% it takes 12.0 g of oil — ₹62.65 of Lavender at 1 kg pricing — and what you pour is 162 g of liquid, not 150 g. That last detail matters more than it looks, because it is where the second convention creeps in, and it is the subject of the next section.

Percentage of wax weight, not of the finished candle

There are two ways to express a fragrance load, and they give different answers. The convention CSI's pages use — and the one this whole series uses — is percentage of wax weight: the oil is measured against the wax it goes into. The other convention measures the oil against the finished candle, wax and oil together. Because the oil is part of that total, the same jar reads lower on the second scale: 16 g of oil in 200 g of wax is 8.0% of the wax and only 7.4% of the 216 g candle.

Going the other way is where the damage happens. If a recipe or a customer specification means 8% of the finished candle, the oil you need on 200 g of wax is 200 × 0.08 ÷ 0.92 = 17.4 g, which is 8.7% of the wax. At the bottom of the range that gap is survivable. At the top it is not: 13% of a finished candle works out at 14.9% of the wax, which is above every maximum CSI publishes. A recipe written in the other convention and poured in this one does not just drift — near the ceiling it takes you straight past it.

Read the last two columns as a warning rather than a recipe. On Luxury Soy Wax CSI 464, whose page states a maximum of 10% of total wax weight, a request for “10% of the finished candle” means 22.2 g on a 200 g pour — 11.1% of the wax, and above the figure. The right response is not to pour it; it is to convert, notice the conflict, and go back to whoever wrote the specification.

Turning a jar into a wax weight

There are three honest ways to get the wax weight for a container, and one dishonest one. The honest ones are: read the fill capacity the jar page publishes; pour one jar and weigh what it took; or, for a container with no published figure, estimate from the water it holds and then confirm with a weighed pour. The dishonest one is to assume that a jar described in millilitres holds that many grams of wax. It does not, and CSI does not publish a density for its waxes, so there is no conversion factor this page can honestly give you.

Where a CSI jar page states a capacity, use it and move on. The Clear Glass Votive Jar is sold as 70 gram, the Clear Glass Jar with Golden Lid as 150 gram, the Borosilicate Glass Jar as 600 gram fill capacity, and the Apothecary Glass Candle Jar in 500 gm and 700 gm sizes. Those are the numbers to multiply. Where a container is sold by volume instead — the Yankee Glass Jar is listed at 130 ML — weigh a test pour rather than treating millilitres as grams.

One caution about the wick column that is not in the table: a 500 gm or 700 gm container is not a scaled-up 150 gram jar. Wide jars need either a much thicker wick or more than one, and CSI does not publish a wick size per diameter on the wick pages, so that is a test-burn question rather than a calculation (wick sizing by diameter). The fragrance arithmetic is identical at every size; the wick arithmetic is not arithmetic at all.

Weigh in grams — millilitres cannot be converted here

CSI sells fragrance oil by weight — 15 gm, 50 gm, 100 gm, 500 gm and 1 kg — prices it by the gram, and states every candle load as a percentage of weight. Wax is sold by weight too. So the entire calculation lives in one unit, and the moment you introduce millilitres you need a density for the oil and a density for the wax, neither of which is published. Different fragrance oils have different densities, so even a rule of thumb borrowed from one oil misleads on the next. Buy a scale, not a measuring jug.

Resolution matters more than range. A scale that reads to 0.1 g and handles 3 kg will cover almost every batch a small maker pours, and the 0.1 g is the important half of that specification. Small candles are unforgiving: a 40 g votive at 8% needs 3.2 g of oil, so half a gram either way moves it between 6.8% and 9.3% — a third of the useful range, on an error you cannot see. The same half gram on a 500 g candle is a rounding difference of a tenth of a point.

This is the practical reason to weigh oil for a batch rather than per jar wherever you can. Pouring twelve votives one at a time means twelve chances to be half a gram out; weighing 67.2 g once into a 840 g melt means one. It is also the reason small-candle makers should sit a point or two below a ceiling rather than at it — not because the wax is fragile, but because their measurement error is a larger fraction of the number.

Scaling to a batch: pour loss, one weighing, and which way to round

Scaling is multiplication again: candles × grams per candle. A hundred 150 g candles is 15 kg of wax and, at 8%, 1,200 g of oil. What trips people is everything around the multiplication — wax left in the pitcher, a melt sized to the exact total, and rounding done in the wrong direction near a ceiling. Three rules handle all of it.

Rule one: melt more wax than the candles need

A few per cent of every melt stays behind — clinging to the pitcher, the spoon, the melter and the rim of the last jar. General practice is to allow 3–5%, more if you are pouring from a wide vessel or working in a cool room where wax sets quickly on the metal. On a 15 kg batch a 4% allowance is 600 g of wax, and the oil scales with it: 15.6 kg of wax at 8% takes 1,248 g rather than 1,200 g. Allow the loss on both, or the surplus wax in the pitcher will be under-fragranced and the last few jars will drift.

Rule two: weigh the oil once, for the whole melt

Fragrance goes into the melt, not into the jars. Add it at the temperature the wax page asks for — Luxury Soy Wax Chunks says 80–90°C with a slow stir of two full minutes, Eco Soy CSI 400 says 85°C within an 80–90°C window — and stir until it is one liquid. A single weighing for the batch is both more accurate and faster than per-jar dosing, and it is the only way to guarantee that jar one and jar fifty are the same product.

Rule three: round the wax up and the oil down

When the arithmetic lands on an awkward figure, round the wax up to the next convenient number and round the oil down to the nearest 0.1 g. Both moves push the load slightly below target rather than above it, which is the safe direction near a stated maximum. Never round oil up to a tidy figure: 1,200 g becoming “about 1,250, close enough” is half a percentage point across an entire batch, and it is the kind of decision nobody records.

Two notes on ordering against these figures. First, buy the pack size that matches the batch rather than the batch you wish you were pouring: Lavender at 1 kg is ₹5.22 a gram against ₹5.40 at 50 gm, but 1 kg of oil at 8% dresses 12.5 kg of wax, which is about eighty-three 150 g candles. Second, CSI's wax variants run to 10 kg; for more than that in one consignment, ask on WhatsApp rather than adding several 10 kg lines to a cart.

Three candles, worked end to end

A 70 gram votive at 8% with Lavender

The Clear Glass Votive Jar is sold as 70 gram, so the wax weight is 70 g and the oil is 70 × 0.08 = 5.6 g. Lavender's page states 6–10% of total wax weight, and CSI 464 states a maximum of 10%, so 8% is comfortably inside both. Materials: ₹35.52 of wax, ₹29.24 of oil, ₹5.90 for an Eco Candle Wicks Thin (C1) and ₹31.86 for the jar — ₹102.52 in materials. Note how the jar dominates a small candle: the fragrance is only a fraction of the cost, which is why dropping a votive from 8% to 6% saves ₹7.31 and is almost never worth the loss in throw.

A 150 gram jar at 10% with Citrus Lemon

The Clear Glass Jar with Golden Lid is sold as 150 gram. Citrus Lemon Fragrance Oil states soy 6–10% and paraffin 6–8%, and CSI 464 states a maximum of 10%, so 10% is the top of both — 150 × 0.10 = 15.0 g. Materials: ₹76.11 of wax, ₹42.48 of oil, ₹5.90 of wick and ₹94.40 for the jar, or ₹218.89. Citrus Lemon is one of the cheaper oils on the list at ₹2.83 a gram, which is why a citrus candle at the top of its range can still cost less in fragrance than a gourmand at 6%.

A 500 gm apothecary jar at 6% with Japanese Cherry Blossom

The Apothecary Glass Candle Jar in its 500 gm size takes 500 g of wax, so 6% is 500 × 0.06 = 30.0 g of oil. Japanese Cherry Blossom publishes 6–13% for candles and describes 6–8% as its light and airy band, which suits a large jar in a bedroom far better than the top of the range would. A jar this wide needs more wick than a votive: two Eco Candle Wicks Thick (C2) at ₹9.44 each is a starting point to test, not a specification. Materials: ₹253.70 of wax, ₹145.26 of oil, ₹18.88 of wick and ₹212.40 for the jar — ₹630.24.

The pattern across the three is worth naming, because it changes how you price. Fragrance is a small share of a small candle and a large share of a large one: ₹29.24 of oil inside a ₹102.52 votive, against ₹145.26 of oil inside a ₹630.24 apothecary candle. If you are trying to protect margin, a percentage point matters on your big jars and barely registers on your small ones — so test loads on the size that actually carries the cost (pricing your candles for profit).

Festive batches, courier timing and the Indian calendar

Festive season is where fragrance arithmetic stops being a private matter and becomes a purchase order. Five hundred 150 g candles at 8% is 75 kg of wax and 6,000 g of fragrance oil — six 1 kg bottles, or ₹31,326.00 of Lavender at 1 kg pricing, on top of ₹38,055.00 of wax. Add a 4% pour-loss allowance and the order becomes 78 kg of wax and 6,240 g of oil. Those are the numbers to send to WhatsApp for bulk pricing, and they are the numbers to send before the middle of October rather than after.

Work the calendar backwards. Diwali 2026 falls on 8 November 2026. A soy container candle wants 14 to 21 days of cure before it is judged, and Indian couriers need their own days on top, so festive stock should be poured by about mid-October — which means the oil has to be in your workshop in the first half of the month, and the calculation has to be right the first time. There is no version of this season in which you re-order fragrance on 25 October and still ship on time.

Two Indian details that belong in the calculation rather than in the hope column. First, heat: oil bottles stored in a workshop that reaches 40°C lose nothing to evaporation if they are sealed, but an open bottle on a bench in an Ahmedabad summer is not a controlled measurement — keep bottles capped between weighings. Second, GST invoicing: if you are buying for a registered business, ask for the invoice at the point of order rather than afterwards, and cost your candles from the invoice figures so that your per-candle fragrance cost is the number your accounts will actually show.

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