How the candle wax calculator works
Candle vessels are sold by volume — an 8 ounce jar, a 30cl tumbler — but wax is bought and weighed by weight. The two are not the same, because wax is less dense than water. To bridge the gap, the calculator multiplies the vessel volume by a fill factor of around 0.86, a widely used approximation for soy and paraffin blends. That gives the weight of wax needed to fill one vessel.
From there the maths is straightforward. Multiply the wax weight per candle by the number of candles to get the total wax for the batch. Fragrance oil is then calculated as a percentage of the wax weight — the fragrance load — which most waxes handle at somewhere between 6 and 10 percent. If you add material prices, the tool converts everything to the same units and totals the wax and fragrance cost per batch and per candle.
Getting the fill factor right
The 0.86 figure is a starting point, not a guarantee. Different waxes have slightly different densities, and how full you pour a vessel affects the number too. The only way to know your exact fill weight is a test pour: weigh the wax that fills one vessel to the level you want, then use that number for your batches. You can adjust the fill factor field to match what you measure.
Why fragrance load matters
Fragrance is often the most expensive ingredient by weight, so the load percentage has a real effect on both scent throw and cost. Going above the maximum your wax can bind does not make a stronger candle — it can cause the oil to seep out, cloud the surface, or affect the burn. Always check the manufacturer's stated maximum for your specific wax, and treat the percentage here as an input you control rather than a fixed rule.
From materials to a sellable price
Knowing your wax and fragrance cost is the foundation, but it is not the full cost of a candle. To price properly you also need to count:
- Wicks and vessels — usually a fixed cost per candle that does not scale with size.
- Packaging and labels — boxes, warning labels, tissue, ribbon.
- Your labour — melting, pouring, curing, cleaning and labelling all take time.
- Overhead — a share of utilities, equipment wear and workspace.
Once every one of those is included, you can apply a markup to reach a wholesale and retail price that actually sustains the business. That full calculation — materials, labour, overhead and margin — is what the BatchCost candle calculator is built to handle.