What fragrance load means
Fragrance load is the weight of fragrance oil as a percentage of the weight of your base: the wax in a candle, the oils in cold-process soap, the base in melt-and-pour soap or lotion. An 8% load means 8 g of fragrance oil for every 100 g of wax.
So this is a fragrance load calculator at heart. It converts whatever you enter to grams, multiplies by the load, and shows the answer in grams and ounces:
Fragrance oil = base weight × load % ÷ 100
The load is a share of the base, not of the finished product. That sounds like a detail, but it is the most common reason a batch comes out weak, especially in soap.
Candle fragrance calculator: a worked example
Say you're pouring 1 lb (16 oz) of soy wax at 8%, the usual starting point:
- 16 oz × 0.08 = 1.28 oz of fragrance oil (about 36 g).
- At 6% the same pound takes 0.96 oz. At 10% it takes 1.6 oz.
- Scaling up keeps the percentage: 5 lb (80 oz) of wax at 8% needs 6.4 oz.
Pick Candle above, enter 1 and choose lb, and you get the same answer. That makes it a fragrance oil calculator for candles of any batch size, as long as you enter the weight of the wax rather than the size of the jar.
Most soy and coconut waxes hold 6–10%. If a candle smells weak at 8%, try a bigger wick and give it a full cure (one to two weeks for soy) before adding more oil. The per-pound breakdown by wax type is in how much fragrance oil per pound of wax, and best fragrance oils for candles covers which oils throw well.
Soap fragrance calculator: a cold-process example
In cold-process and hot-process soap, the percentage is of your oils and butters: the olive, coconut, shea and the rest. Not the lye, not the water, not the finished bar. Working it out on total batch weight under-doses by about a third.
A recipe with 32 oz (2 lb) of soap oils at 5%:
- 32 oz × 0.05 = 1.6 oz of fragrance oil (about 45 g).
- At 3% it's 0.96 oz. At 4% it's 1.28 oz.
In the calculator, pick Cold-process soap and enter your total oil weight. It starts at 4%, the middle of the 3–5% range; set 5% for a scent that has to last through a four-to-six-week cure. Melt-and-pour is different: the percentage is of the base weight, and the base only holds 1–3%.
The soap fragrance calculator gives you the amount; the oil decides how the batch behaves. Some oils speed up trace or turn soap brown. How much fragrance oil per pound of soap covers when to add it in each method, and best fragrance oils for soap making covers which oils behave.
Safe maximum rates, and why they exist
The range next to the load field is a safe starting point for that product, not a permission. Two things set the real ceiling, and one thing people expect to matter mostly doesn't.
IFRA limits. IFRA, the fragrance industry's safety body, sets a maximum percentage for each oil in each product category. The categories follow skin contact. Candles, wax melts and diffusers never touch skin, so they allow the most. Soap is washed off, so it sits in the middle. Lotion and other leave-on products stay on skin for hours, so they get the lowest limits. Your supplier lists these on the oil's IFRA certificate. An oil rated for candles is not automatically safe in lotion, and if the certificate says less than our range, the certificate wins.
What the base can hold. Wax can only bind so much oil, about 10% for most soy and coconut waxes. Past that, oil sweats onto the surface, the wick clogs, and the flame can run large and sooty. More oil does not mean more scent. Melt-and-pour soap does the same at much lower rates: overload it and the bars weep.
Flash point. This is the temperature at which an oil's vapor can catch fire from a spark or flame. It matters for shipping and handling, not for how much you add, and a higher flash point does not make a stronger candle. Add fragrance at the temperature your wax maker gives, often around 185°F (85°C) for soy, with the wax off the heat.
Every product's working range is in the fragrance oil usage rates guide, and what is IFRA explains how to read a certificate.
Ounces vs grams
Fragrance load is a weight percentage, so measure everything on a scale. The ounces here are weight ounces (1 oz = 28.35 g, and 1 lb = 16 oz = 454 g), not fluid ounces. A fluid ounce of fragrance oil does not weigh an ounce, so a measuring cup gives you the wrong amount.
Grams are easier for small and test batches because the numbers stay round: 500 g of wax at 8% is 40 g of oil, and 500 g of soap oils at 5% is 25 g. If you choose ml, the calculator treats 1 ml as 1 g. That is close for water-based room sprays but runs high for alcohol and oils, which weigh less than water, so weigh those when you can.