Candle Wax Calculator

Wax is bought by weight but poured by volume, so the bridge is density: wax weight = vessel volume × wax density. Container waxes are lighter than water — soy runs about 0.86 g/ml, paraffin ~0.90, coconut blends ~0.92, beeswax ~0.96. An 8 fl oz (237 ml) jar therefore takes roughly 204 g of soy wax, not 237 g. Multiply by the batch count and you have the wax to weigh out.

The number people get wrong is the fragrance load. Industry convention defines it as a percentage of the wax weight: a 10% load in 204 g of wax is 20.4 g of oil, and the candle then weighs 224 g total. (Some suppliers quote “% of total” — that 10% would be 20.4 g of oil in 204 g of finished candle, i.e. 185 g of wax. This calculator uses the wax-weight convention, which is what most fragrance houses’ max-usage tables assume.) Most container waxes hold 6–10% fragrance; above that the oil weeps out or the flame flares.

The label on the jar is the overflow volume — filled to the brim — but nobody pours to the brim. A candle is poured to a fill line about 1–2 cm below the rim, which in a typical 8 oz jar is more like 6.5–7 oz of actual wax. Sizing a batch from the label volume is the most common reason beginners melt 15% too much wax.

The accurate method takes thirty seconds: put the empty vessel on a kitchen scale, tare it, fill it with water to your intended fill line, and read the weight. Grams of water equal millilitres of volume (water is 1.00 g/ml), so 200 g of water means a 200 ml fill. Enter that volume in the calculator and the density factor converts it to the wax weight — wax is lighter than the water you measured with, which is exactly why weighing the vessel filled with water does not give you the wax weight directly. Do this once per vessel design and save it as a preset.

Start at 6–10% of the wax weight: 6% gives a subtle scent that suits bedrooms and diners, 10% is the strong throw most sellers aim for. The ceiling is set by two different documents. The wax maker’s maximum load (often 10–12% for modern soy blends) is what the wax can physically bind; the fragrance house’s IFRA max-usage figure for “category 12 / candles” is the safety cap for that specific oil, and it can sit well below the wax’s capacity. Use the lower of the two — the calculator’s load field does the arithmetic, but the cap is your supplier’s call.

More oil is not more scent. Past the wax’s binding capacity the excess oil seeps out as wet spots on the surface, and an over-loaded wick spits and flares. If a candle smells weak at 10%, the fix is usually the pour temperature, the cure time (soy needs 1–2 weeks of curing for full cold throw) or the oil itself — not a higher percentage.

The calculator’s working densities are the standard supplier values: soy 0.86, paraffin 0.90, coconut blend 0.92, beeswax 0.96 g/ml. The spread looks small but compounds across a batch: the same 237 ml jar takes 204 g of soy but 228 g of beeswax — an 11% difference in how much wax you need to buy.

Blends vary by a few percent between brands and even between a supplier’s container and pillar formulas — a GoldenWax 464-style container soy and a parasoy pillar blend do not share a density. For a production run, calibrate once: weigh the wax that fills one jar to your line, divide by the jar’s water volume, and you have your wax’s true density to three decimals. Until then, the defaults will land you within a few grams per candle.

Three temperatures matter and they are different. Melt container soy to about 185°F / 85°C — hot enough to fully liquefy and to bind fragrance. Add fragrance around 185°F / 85°C for soy: adding it too cool is the classic cause of weak cold throw and weeping oil, because the oil never fully binds into the wax matrix. Then let the wax cool to the pour temperature — roughly 135–145°F / 57–63°C for most container soy — before filling jars; pouring hot causes sinkholes, wet spots and frosting.

Paraffin container blends behave similarly but pour a touch hotter (around 150–160°F); beeswax pours hottest of all, around 155–165°F, and shrinks enough on cooling that a second top-up pour is almost standard. Always follow the specific wax’s data sheet over any general chart — and warm the jars (a low oven or a heat gun) before pouring, because cold glass shocks the wax into pulling away from the sides.

Wick size scales with the diameter of the melt pool, which for a container candle is the vessel diameter. As a starting range: a single wick handles vessels up to roughly 65 mm across, medium vessels of 65–80 mm want the upper sizes of a series (a CD 12–14 or ECO 10–12 for a 70 mm jar in soy), and past 80 mm most makers switch to two smaller wicks rather than one giant one. The target burn: a full melt pool reaching the glass within 3–4 hours, a steady flame, no smoking, no mushroom of carbon on the tip.

Every published wick chart — including this calculator’s note — is a starting point, not an answer. Fragrance oil makes the fuel thicker, dye darkens it, and harder waxes like beeswax need a size or two up from soy at the same diameter. The only authoritative test is a burn test: make one candle per candidate wick, burn in 4-hour sessions, and keep the one that reaches a full pool without drowning or sooting. Budget the extra wax for testing into the batch — it is what the 5–10% overage is for.

The calculator’s per-candle figure is what lands in the jars, not what you melt. Add 5–10% for the batch: wax that stays filmed on the pouring jug, the thermometer and the melting pot, plus a reserve for the second top-up pour that levels sinkholes as container wax cools. For a six-jar soy batch at 1,223 g of jar wax, that means buying at least 1.3 kg — 1.4 kg if you plan a generous top-up.

First batch with a new vessel, wick or fragrance? Make one extra candle’s worth on top. You will want a test burn anyway, and a cracked jar or a mis-centred wick on candle four should be an inconvenience, not a shortfall. Wax keeps for years in a sealed bag away from light; leftover is inventory, not waste.

A batch of six 8 fl oz jars in soy wax at a 10% load. Wax per jar: 237 ml × 0.86 = 204 g. Batch wax: 204 × 6 = 1,223 g. Fragrance: 1,223 × 10% = 122 g (about 4.3 oz). Total pour weight: 1,345 g, or 224 g per jar. Buy at least 1.3 kg of wax — add another 5% if you plan a second pour to fix sinkholes, so call it 1.4 kg.

For a 70 mm diameter jar, start testing around a CD 12–14 or ECO 10–12 wick: the target is a full melt pool to the glass in 3–4 hours without smoking or a mushrooming tip. Wick charts are starting points — wax, fragrance and dye each shift the answer, which is why every serious candle line burn-tests each combination.