Candle Wax Calculator

In short Wax is sold by WEIGHT and containers are measured by VOLUME, and almost every first-batch ordering mistake lives in that gap. Density is the bridge. A 300 ml jar filled to 90% holds 270 ml of wax, and soy at about 0.90 g per millilitre makes that 243 grams — not 270. Treating millilitres as grams over-orders by around 11%, every jar, every time. THERE ARE TWO ROUTES AND THEY MUST GIVE THE SAME NUMBER. The volume route multiplies the stated capacity by the fill level and the density. The water route is the one suppliers teach: fill the jar to your pour line with water, weigh the water, and multiply by the wax density. Here that is 270 grams of water times 0.90, which is the same 243 grams. They agree because water is one gram per millilitre by definition, and the water route is worth knowing because on an odd-shaped jar the stated volume is a guess while the water is a measurement. AND IT WILL SINK, BY A FIXED FRACTION. Wax is less dense hot than cold, so the pour shrinks as it sets. Going from about 0.85 g/ml liquid to 0.90 solid is a 5.6% drop in volume, and the mass cancels out of that fraction entirely — a tealight sinks by the same percentage as a three-wick. That is why the dip in the middle is universal, why the wick end lifts, and why a second pour exists as a technique rather than a fix for a mistake. Two things this page leaves to you. The fill level is a choice, not a constant: leaving headroom keeps the wick trimmable and the lid clear, and the difference between 90% and 100% across a batch is real wax. And the densities are conventions, editable above, because blends differ and pour temperature moves the liquid figure. Weigh a known volume of your own wax once and every number here becomes yours instead of typical. Fragrance is not included in this weight; it is added on top of it.