How much wax for six 200 mL jars?

In soy at 85 per cent fill, 153 g per jar and 918 g for six — round to a kilogram, because a pour always leaves wax in the pouring jug. In beeswax the same six jars take 979 g. Add your fragrance on top of the wax weight, not inside it: at eight per cent that is another 73 g for the soy batch.

Does the wax shrink as it sets?

It does, by a few per cent, and that shrinkage is why a first pour often needs a second. The mass does not change — you have the wax you weighed — but the volume drops as the wax crystallises, which pulls the surface down and can open a well around the wick. Pour warm, pour slowly, and keep a hundred grams back for a top-up rather than trying to compute your way around the physics.

Why does my candle smell weak even at the maximum load?

Load is only half of it. Scent throw depends on the wick pulling a wide enough melt pool to release the oil, on the oil being added at the right temperature — too hot and the top notes flash off, too cool and it does not bind — and on the candle curing, which takes one to two weeks for soy. A candle that smells weak on day two very often smells right on day ten with nothing changed. Adding more oil past the wax's limit does not fix any of those and produces sweating instead.

A Jar Is Sold by Volume and Wax Is Bought by Weight

Published 9/11/2026 · 5 min read · Everyday calculators

Antonio Delgado — Traditions & pastimes writer at OneKitly

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In short

A container is rated by the volume of water it holds, and wax is sold by mass, so the bridge is the wax density and the fill level: wax weight = container volume × fill fraction × density. A 240 mL jar filled to 85 per cent with soy at 0.90 g/mL takes 183.6 g. The maker's rule of thumb — about 0.8 ounces of wax per fluid ounce of jar — works out to an effective density of 0.767 g/mL, which is soy at an 85 per cent fill and nothing else. It is within 0.2 per cent for soy, paraffin and palm, two per cent low for coconut and six per cent low for beeswax at 0.96 g/mL.

The trade rule of 0.8 oz of wax per fluid ounce of jar is an effective density of 0.767 g/mL — calibrated for soy at an 85 per cent fill. It is right to within 0.2 per cent for soy and under-reads beeswax by six.

Where the 80 per cent rule comes from

Work the rule backwards and it stops being folklore. Eight tenths of an ounce of wax per fluid ounce of jar is 0.8 × 28.3495 grams divided by 29.5735 millilitres, which is 0.767 grams per millilitre. Divide that by the 0.90 g/mL of soy wax and you get 85.2 per cent. The rule is not a rule about candles at all: it is soy wax at an eighty-five per cent fill, expressed in the units an American supplier prints on a jar.

That makes it accurate exactly where it was calibrated and wrong everywhere else, in a predictable direction. Beeswax is the heavy one at 0.96 g/mL, so the rule under-orders it by six per cent — on a batch of thirty jars that is more than a kilogram of wax you thought you had. A shallow fill goes the other way: at 70 per cent rather than 85, the same soy jar needs 151 g, and the rule over-orders by twenty-two per cent.

Fragrance is a percentage of the wax, never of the total

A fragrance load of eight per cent means eighty grams of oil per kilogram of wax, giving a finished 1,080 grams. Read the same eight per cent as a share of the finished candle and the arithmetic inverts: to make oil eight per cent of the total you need 87.0 grams, not 80 — 8.7 per cent more oil than the supplier's maximum allowed. That is enough to push a wax past the load it can hold, and the symptom is oil sweating out of the surface days later.

The windows differ sharply by wax, and they are not preferences. Soy and paraffin hold six to ten per cent, coconut eight to twelve, beeswax only three to six — a natural wax with a scent of its own that will not absorb much added oil. A recipe written for coconut and poured in beeswax is over-loaded by a factor of two before anyone has made a mistake.

Measure the jar, do not trust the label

A jar sold as eight ounces is describing a nominal capacity, usually measured brim-full, and no candle is poured brim-full. The reliable measurement takes a minute: put the empty jar on a scale, tare it, fill it with water to the line you actually intend to pour to, and read the grams. One gram of water is one millilitre, so the scale has just given you the volume that matters instead of the volume on the box.

The fill level itself is a decision and not a constant. Too high and there is no headspace, so the wick sits proud of the wax and the first burn drowns; too low and the candle looks mean and tunnels. Eighty to eighty-five per cent is the usual band, measured from the inside bottom to a centimetre or so below the rim, and a straight-sided jar makes it easy to hold. A tapered or rounded jar does not, which is the second reason to measure with water rather than compute from a shape.

Density

A 240 mL jar at 85 per cent fill: what each wax actually weighs
Wax	Density	Wax needed	The 80 % rule says
Soy	0.90 g/mL	183.6 g	184.1 g — +0.2 %
Paraffin	0.90 g/mL	183.6 g	184.1 g — +0.2 %
Coconut	0.92 g/mL	187.7 g	184.1 g — −1.9 %
Beeswax	0.96 g/mL	195.8 g	184.1 g — −6.0 %

Frequently asked questions

How much wax for six 200 mL jars?: In soy at 85 per cent fill, 153 g per jar and 918 g for six — round to a kilogram, because a pour always leaves wax in the pouring jug. In beeswax the same six jars take 979 g. Add your fragrance on top of the wax weight, not inside it: at eight per cent that is another 73 g for the soy batch.
Does the wax shrink as it sets?: It does, by a few per cent, and that shrinkage is why a first pour often needs a second. The mass does not change — you have the wax you weighed — but the volume drops as the wax crystallises, which pulls the surface down and can open a well around the wick. Pour warm, pour slowly, and keep a hundred grams back for a top-up rather than trying to compute your way around the physics.
Why does my candle smell weak even at the maximum load?: Load is only half of it. Scent throw depends on the wick pulling a wide enough melt pool to release the oil, on the oil being added at the right temperature — too hot and the top notes flash off, too cool and it does not bind — and on the candle curing, which takes one to two weeks for soy. A candle that smells weak on day two very often smells right on day ten with nothing changed. Adding more oil past the wax's limit does not fix any of those and produces sweating instead.

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