Candle Making Mathematics: How To Accurately Calculate The Correct Amount Of Wax And Fragrance Oil By Weight

When making candles, it’s vital you get your measurements right. If you prepare too much wax and fragrance for the amount of vessels you have on hand, it’s a waste. But you also don’t want to end up with not enough. Point is, you need to know exactly how much wax and fragrance oil you will require to create a candle.


Here's How!


(Although this might seem a little dry and daunting for newcomers, it will soon become second nature. I wasn’t a huge fan of maths at school but for a constructive application like candle making, connected with a new incentive, it’s not too bad.)


Step 1.

How much wax do you need?

Let’s work out the jar fill volume

  • Choose your vessel.
  • Check the product information from your supplier. Do they note anywhere the volume of the vessel in grams for wax? Most companies will work this out for you prior to purchase. If you answered yes, then skip ahead to step 2. If not, you’ll need to work it out on your own.


The simplest way work it out is:

Measure how much water fills your vessel by weight (ie in ml or grams).



How much candle wax do you need?


  • Tare your scale back to zero after placing the vessel on the scale and before filling with water. You want to ensure you’re measuring the weight of the water only.
  • Only fill up your vessel to where you want your candle to stop ie: not right to the top. You want to leave approximately 1 cm for the wick—depending on your design.
  • Alternatively, if you don’t have a scale, you can simply pour the water from your vessel into a jug which shows measurements in ml. Mls are the equivalent to grams ie: 1ml = 1 gram—please note this equation applies to pure water only, not wax.


Ok, great! We now have the quantity that we'll need to fill the vessel, but the measurement is for water, not wax, so we need to convert it.

In candle making, it is necessary to measure wax by weight and not by volume. You might assume that the same amount of water that fills the vessel will be the same measurement in wax, but that is mistaken. Although wax transforms from solid to liquid when melted, wax is not the same weight as water. In fact, candle wax is less dense than water, so it weighs less.

Candle wax is around 90 percent as dense as water, so it has a specific gravity of 0.90 as opposed to 1 which would mean that it’s the same as water. Wax takes up more space than water in your vessel. If you measured the same amount of wax as water, you would end up with too much wax.

Wax comprises carbon and hydrogen atoms, water comprises oxygen and hydrogen atoms. Oxygen atoms are heavier & smaller than carbon atoms. Therefore, wax floats on water.

Now let’s do the conversion:

Let’s say you have a 200ml/g container.

You don’t want to fill it up all the way to the top, because you need to leave 1cm from the top, so you only fill it with 150 ml/g of water.

The equation is: 150 grams (ie: the level of water) x 0.90 (this equation converts the density of water into the weight of wax) = 135 grams. And that is how much wax you will need for that container.


Step 2:

Wax Needed For Multiple Vessels

Now that you’ve worked out that you need 135 grams of wax to fill this one vessel, you can calculate the amount of wax you’ll need for more containers.  

Multiply the total 135 grams by the number of vessels you want to fill. If you want to make 20 vessels, then 135 grams x 20 vessels = 2700 grams (2.7kg).

 Wax for candle making


Step 3:

Adding Fragrance to the Equation

The above calculations are for the wax only. They do not include fragrance. But remember, we still need space in your empty vessel for fragrance (if you intend to use it). If you were simply to add the fragrance to the wax quantity above, you would end up with wastage.

Now we’re going to work out how much wax to minus from the vessel to make space for the fragrance too.


Candle fragrance


If you choose a 10% fragrance load for your single vessel which requires 135g of wax, the fragrance calculation would be:

135g wax x 10% = 13.5 grams of fragrance required

Then we remove this fragrance requirement from the total of wax:

Empty vessel takes 135 grams wax minus 13.5 grams fragrance for a 10% load = 121.5 grams wax needed for one vessel, and not the 135 grams as we formerly thought.


Soy wax candle making


Still feeling confused?

Join us for a virtual candle making class.




Leave a comment

All comments are moderated before being published