Candle Wax Calculator
Weigh water to your container's fill line and get the exact wax weight in grams and ounces for any batch size.
Fill one container with water to the line you want the finished wax to reach, then weigh that water in grams (1 ml of water weighs 1 g). Melt a bit extra to cover what sticks to your pour pot and pitcher, and leave headspace below the rim so the wax doesn't overflow.
How it works
The easiest way to know how much wax a container needs is to skip the guessing and weigh it directly. Fill the empty container with water up to the line where you want the finished candle to sit, then pour that water onto a scale and note the weight in grams. Since 1 ml of water weighs 1 g, that number is your fill volume. Wax is lighter than water, so the calculator multiplies your fill amount by 0.86 (soy wax; paraffin comes in close enough for planning purposes) and by however many containers you're pouring.
Worked example: you fill one jar to the line and it holds 250 ml of water, and you're making 4 of them. The calculator does 250 × 0.86 × 4 and rounds to 860 g of wax, which is 30.3 oz if your scale reads in ounces. A single 200 ml jar comes out to 172 g. Melt a little more than the number the calculator gives you, since some wax always sticks to the pour pot, pitcher, and stir stick, and leave a bit of headspace below the rim so the poured wax doesn't crest over the edge.
FAQ
Why weigh water instead of just guessing?
Eyeballing wax amount by container size wastes wax (if you melt too much) or leaves you short mid-pour (if you melt too little), and re-melting a second batch mid-project throws off your fragrance timing. The water-weigh method takes two minutes and gets you within a few grams every time, regardless of the container's shape.
Does the 0.86 ratio change by wax type?
It's dialed in for soy wax, which is what most beginners start with. Paraffin and coconut blends are close enough in density that the same ratio works fine for planning how much to melt. If you're working with a wax that has a printed density on the bag, that number will always be more precise than a general ratio.
How much extra should I melt?
A good rule of thumb is 10 to 15% more than the calculator's number, especially for your first batch, since wax clings to the melting pot, pouring pitcher, and any stir tools. Extra wax isn't wasted. It just goes back in the pot next time.
What if I'm using a mold instead of a jar?
Same method: fill the mold with water to the fill line, weigh it, and use that number as your container fill amount. Pillar and mold candles use the same 0.86 ratio as container candles.
For more on getting the right amount and pour, see how much wax you need for a candle, how to pour a soy candle step by step, and the best containers and vessels for candles.