How do you measure the amount of candle wax and fragrance oil for candle making? We all love the fragrance when you walk past an aisle of scented candles.
Hmmmmm, you inhale, dream and exhale.
Scents trigger memories, just like when I caught a whiff of petrichor (smell of rain) and was quickly reminded of home. Believe it or not, scents affect memory. When you sniff something, good or bad, it sends signals to the olfactory bulb (the brain’s smell center). This part of the brain is directly linked to areas that control mood, emotions, behaviour… and MEMORY.
This is one of the reasons scented candles play an important role in therapy. You’ve probably learnt the process of candle making and maybe, gotten the kit. But, what ratio of fragrance oil to candle wax should you use? How much candle wax and fragrance oil do you need? How do you calculate the amount of wax and fragrance oil you’ll need to make your scented candles?
Candle wax and fragrance oil calculations made super easy.
How much fragrance oil to use in your candle depends on the wax type, fragrance oil and your preferred scent throw. Too much fragrance oil may result in strong hot throw and potentially overload the wax leading to what is called curdling or sweating. On the other hand, using too little fragrance oil may end in low scent throw. So, finding the optimum balance is one of the recurring issues faced by candle makers during the candle making process, this includes seasoned/pro candle makers.
The fragrance load of your candle also affects the type of candle wick, how the wick burns, and the melt pool. Fragrance load ranges from 3% to 10%, with 6% being the most common.
Remember in my announcement of my candle making journey, I said there is science to it so here you will learn how to
We’ll be applying both science and mathematics skills. So, buckle up!!
First thing you will need is a scale. Due to the variability in physical properties of waxes and fragrance oil with temperature and the type of wax, all measurements are done by weight. So, always remember to use the mass (in grams or ounce), and not the volume (mL, fl oz. etc.). That being said, the first thing you will need, beside the wax and frag oil, is a scale.
Then, follow the steps below which explains how I make my calculations. I have also created a candle making calculator which takes away the manual calculations. You won’t believe but it is FREE. Download it below.
1. Determine the weight of your candle container
How heavy your candle is depends on the size of your container, or mould, and how much wax it can carry. Water is always used for this calculation but, REMEMBER! water is more dense than wax so, don’t expect the same volume of water to weigh the same as wax. SPECIFIC GRAVITY! my friends. This is why we use the mass.
If you insist on using volume measurements, then you will need to know the density of your selected candle wax. Remember your chemistry class, people!
Knowledge of the specific gravity or density of the wax will be useful in this calculation. Density of natural waxes varies between 0.8 to 0.9 g/mL, for instance, soy wax density is 0.9 g/mL. Though, an average of 0.86 g/mL is commonly used when working with natural candle wax.
Converting a specific gravity into a density is as simple as multiplying the SG by the reference density for which it was based. In most cases, this is the density of water, and therefore your multiply the SG by 1 to yield your density in g/cm^3.
Follow the steps below to calculate the net weight of your candle,
- Fill the container to the desired fill line with water. It is recommended to use at most 90% of your container volume, this excludes moulds. Remember to tare the scale to remove the container weight before measuring.
- Record the mass (g or oz).
- Multiply the mass of water by specific gravity of the wax.
- If you were the stubborn person that used volume, then measure the volume of water that fills your container to the fill line then multiply that volume by density of the wax to get the total mass of the candle. And stop being stubborn!! *rolls eyes*
2. Decide on the fragrance oil load (%)
You will need to experiment to find what best suits you and your candle. The typical range for the ratio of fragrance oil to wax, as I mentioned earlier, is 3-10% but a great starting point is 6%. For our case study, we will use 10%.
3. Calculate the amount of candle wax to use
Now you know the total mass of your candle, how do you calculate the amount of wax in a candle. Meaning how much of the scented candle is wax. I determine that value by dividing the total mass of the candle (step #1) by the sum of 1 and fragrance load. Recall, the total mass is the amount of the wax plus FO so the formula below will give the wax amount.
[Wax amount (g)] = [Total mass of candle or container capacity (g)] / [1 + Fragrance oil load (%)]
The result you will get is for a single candle so multiply that value by the number of candles you want to make using similar containers.
We still need to know how much FO to use, which was the main question of this post, how much fragrance oil do you need?
4. Determine how much fragrance oil you need
If you’ve come this far bravo. Calculating the fragrance amount can be done in two ways and both are pretty straightforward. Remember, we’re working with the mass (g or oz).
#1: Fragrance amount (g) = Total mass (g) – Wax amount (g)
#2: Fragrance amount (g) = Fragrance load (%) x Wax amount (g)
Again, if you’re making more than one candle, multiply the value by the number of candles you’ll be making (only valid for identical containers).
Tip: If you’d like to know the volume of FO needed so you can decide on how much to order or to figure out if the amount you have in stock is realistic to make the ambitious number of candles you’ve been dreaming of. Simply divide that calculated mass of FO (g) by its density and you will get the volume. I realised that just like the wax, fragrance oil density are typically between 0.8 – 0.9 g/mL.
Now, let’s put this to context.
Example
How much candle wax and fragrance oil do I need to make 10 candles each weighing 120 g with a strong scent throw.
Step 1: Determine the weight of the candle container.
Already decided, 120 is my net size in g. But for clarity, measure the container when empty (let’s say it’s 60 g) and when filled with water (let’s say it’s 200 g). Subtract the mass of empty container from mass of filled container (answer = 140 g). Then, multiply your answer by the specific gravity (I said 0.86 so 140 g x 0.86 = 120 g) to get the total mass of the candle.
So, total mass is 120 g
Step 2: Figure out fragrance oil load
I want a really strong throw and I’ve decided 10% of the wax weight should be fragrance oil.
Step 3: How much wax do I need?
Wax amount (g) = [120 g] / [1 + 10%] = 120 g / 1.1 = 109.09 g*
Since I want to make 10 candles,
Total wax amount (g) = 10* 109.09 g = 10,909 g
*most kitchen scales have 0 decimal places so you may have to round up
Step 4: Calculate the amount of fragrance oil
I want a 10% loading of FO using the two formulas. See!! you can use either of the two formulas.
#1: FO = 120 g – 109.09 g = 10.9 g
#2: FO = 10% x 109.09 g = 10.9 g
Again, we need this for 10 candles so,
FO = 10 x 10.9 g = 109 g
Hence to make 10 candles, each weighing 120 g, you will need 10,909 g wax and 109 g fragrance oil. YOU GERRIT!!!
Add your questions or comments or tips in the comment section.
