How much wax does a candle need?
The short answer is that wax fills space, so the size of your container decides everything. The longer answer — and the reason a calculator helps — is that wax is sold by weight but jars are measured by volume, and the two only line up once you know how dense your particular wax is. Soy wax, for instance, weighs about 0.86 grams per millilitre, so a 240 ml jar filled to 90% takes roughly 186 grams rather than 240.
A tip worth remembering: always melt a little more than you need — around 10% extra. Wax clings to the sides of the pouring jug and cools quickly, and there is nothing more frustrating than being twenty grams short with three jars already wicked and waiting.
Understanding fragrance load
Fragrance load is the proportion of scent to wax, given as a percentage of the wax weight. A 10% load means 10 grams of fragrance oil for every 100 grams of wax, and that is the standard most container waxes are designed for. Going higher doesn't always mean a stronger scent — beyond what the wax can hold, the oil simply seeps out, leaving damp patches on top and a candle that burns poorly. Check what your particular wax will take before reaching for 12%.
Getting the wick right
The wick suggestion above is a starting point based on your container's width, not a promise. Wick choice depends on the wax, the fragrance and even the colour you've added, so seasoned candle makers always test. Pour one candle, let it cure, and burn it for a few hours: you want a melt pool that reaches the edges within two hours or so, with no soot and no drowning flame. Too small a flame means going up a wick size; a tall flickering flame with black smoke means going down.
Why you should let candles cure
A candle poured today is not at its best today. Soy in particular needs a week or two for the fragrance to bind properly into the wax — burn it after a day and you'll wonder where the scent went. Pour, wick, wait, then test. Patience genuinely makes a better candle.
Questions we're often asked
How much wax do I need for an 8 oz candle jar?
An 8 fluid ounce jar holds about 237 ml, which takes roughly 183 grams (6.5 oz) of soy wax at a 90% fill, plus about 18 grams of fragrance oil at a 10% load. A useful rule of thumb: the wax weight in ounces is about 80% of the jar's fluid-ounce size.
How do I calculate wax for an odd-shaped container?
Fill the empty container with water to your intended fill line, then pour that water into a measuring jug. That reading is your volume in millilitres — enter it in the "I know the volume already" option above and the calculator does the rest.
What is the standard fragrance load for soy wax?
Most soy container waxes are formulated for 6% to 10%, with 10% being the common choice for a good scent throw. Some waxes will take up to 12%, but adding more than the wax can hold causes seeping and poor burning rather than stronger fragrance.
Should I weigh fragrance oil or measure it by volume?
Always weigh it. Fragrance oils vary in density, so a spoonful of one is not the same as a spoonful of another. Digital kitchen scales that read to one gram are perfectly adequate and will make your candles far more consistent.
Why did my candle sink in the middle?
That's a normal quirk of soy wax cooling unevenly, not a mistake on your part. Pouring a little cooler, cooling more slowly in a warm room, or keeping a small amount of wax back for a second top-up pour will all help.