How much wax do I need for candles?
A jar is sold by volume and wax is bought by weight, so the two numbers never match. Here is the conversion for every common container.
A candle takes roughly 91 g to 366 g of wax depending on the container, which is always less than the jar’s stated size. An 8 oz jar holds about 8 fluid ounces of liquid, but only around six and a half ounces of soy wax by weight, because wax is lighter than water and you leave headspace at the top.
This is the first thing that trips up a new candle maker, and it trips up nearly all of them. You buy an 8 oz jar, you buy 8 oz of wax, and you end up with a jar that is a quarter empty.
The reason is that the two eights are measuring different things. A jar labelled 8 oz holds eight fluid ounces — a volume. Wax is sold in ounces of weight. Wax is lighter than water, so the same space holds less of it, and on top of that you never fill a container to the brim.
The table below does the conversion for every common container size. If your vessel is not on it, or it tapers, use the wax calculator — it takes a water weight, which measures the shape of your actual jar rather than the number on the label.
Wax needed, by container
Soy wax at a standard fill with headspace. Computed from the same density factors the wax calculator uses, so these figures and the tool always agree.
The same jar in three different waxes
The container default, and what most recipes assume unless they say otherwise.
Marginally denser than soy, so the same jar takes a little more by weight.
The densest of the common waxes. Still well short of the jar’s stated size.
What actually changes the number
A stated volume assumes a straight-sided jar filled to the brim. A tapered tumbler, a thick glass base or a curved shoulder all hold less than the label implies. Weighing water to your pour line is the only way to measure the vessel you actually have.
Filling to the brim is only for moulds. A container needs room for the lid to sit clear of the wax — a standard fill of 90% is the usual compromise, and dropping to a more generous headspace takes several grams off every candle.
Density varies less between waxes than most people expect. Across the common container waxes the factor moves only a few percent, so switching from soy to a coconut blend changes the weight far less than switching jars does.
Most recipes add fragrance oil on top of the wax weight, so the finished candle weighs slightly more than the figures here. If you are working to a target finished weight instead, the fragrance calculator handles both conventions.
Wax clings to the pouring jug, the thermometer and the spatula. Order about 10% over the calculated total or you will come up short on the last jar of a batch.
Getting it right the first time
Fill the empty vessel with water to exactly where you want the wax to sit and weigh it in grams. That figure, multiplied by your wax factor, is your answer — no fill-level guessing needed.
Ounces of weight and fluid ounces of volume look identical on a label and are the source of nearly every wax mix-up. Grams and millilitres cannot be confused with each other.
Melting one jar at a time wastes wax on the jug every single pour. Melting a batch loses it once.
Once you know a vessel takes a certain weight, that never changes. A note on the shelf where you keep them saves you doing this again.
Work out your own vessel
Enter a volume or a water weight and get the exact figure for your jar, your wax and your batch size.
Open the wax calculator →Print the numbers you keep looking up
One printable page — wax, fragrance load, wick sizing and pour temperatures. Free.
Estimates, not advice. Every figure on this page is computed from published reference values and standard measures, so your own inputs, equipment and conditions will move it. Nothing here is professional advice — talk to a qualified professional before acting on it.