How Much Fragrance Oil Should I Use in Soap?
Short answer: for cold process and hot process soap, most soapers use around 5% of their oil weight. That's about 0.8 oz (23 g) of fragrance per pound of oils. Go as low as 3% for a light scent, or up to 6% for a strong one. Melt and pour uses less: 1% to 3% of the base. Always weigh your fragrance, and never go over its IFRA limit for soap.
Our usage rates
These are the rates our fragrance calculator uses. Most soapers land around 5%, between medium and strong. Save the 3% light rate for when you want a very light scent.
| Strength | Cold and hot process (% of oil weight) | Per pound of oils | Melt and pour (% of base) |
|---|---|---|---|
| Light | 3% | about 0.5 oz (14 g) | 1% |
| Medium | 4.5% | about 0.7 oz (20 g) | 2% |
| Strong | 6% | about 1 oz (27 g) | 3% |
For cold process, figure the percentage from your oil weight, not your whole batch. Water leaves the soap as it cures, so we don't count it.
How to work it out
- Turn the percentage into a decimal: 5% is 0.05.
- Multiply by your oil weight. For 32 oz of oils: 32 x 0.05 = 1.6 oz of fragrance.
- Weigh it on a scale. Drops and teaspoons aren't accurate enough.
IFRA comes first
Every fragrance has a maximum safe amount for soap, set by the International Fragrance Association (IFRA). Soap is Category 9 on the IFRA certificate. If a fragrance's Category 9 limit is lower than the rate you want, the IFRA limit wins.
- Every Nurture fragrance has its IFRA certificate on the product page.
- For other brands, ask the seller for the IFRA certificate before you buy.
- We label fragrances with a Category 9 limit under 4% as not recommended for soap. Here's why: Why Does My Fragrance Oil Say It's Not Recommended For Soap?
For more on reading the certificate, see Reading IFRA Fragrance Rates and How to Use a Fragrance Oil Calculator.
Too much or too little
- Too much can speed up trace, bead on cured bars, irritate skin, and costs more. See Why Did My Soap Seize or Thicken So Fast? and Why Is My Soap Sweating or Weeping?
- Too little smells great in the pot and faint after cure. See Why Did My Soap Lose Its Scent?
- Some fragrances are strong, so a light rate is plenty. Start in the middle and adjust next batch.
Want us to work it out for you?
Put any fragrance into Fragrance Check, and it finds the IFRA limit and tells you how much to use for your soap. Already made the soap and something went wrong? Tell us in Fragrance Rescue.