How Much Essential Oil to Add to Soap? (Soap Making Guide)

By Marsha Harrison

Fact-checked by Kia Lowe

how much essential oil to add to soap

Essential oils are becoming increasingly popular by the day because of their natural properties. It is used to create an atmospheric scent in a room, as a body oil, and even as part of many’s skincare routines.

If you are interested in creating your own DIY soap, you must be wondering exactly how much essential oil to add to soap?

There is no set standard on the amount of essential oil you can add to soap since the percentage changes depending on IFRA standards and personal preference.

Factors Affecting Essential Oil Usage in Soaps


Most people prefer essential oil in soaps because it is a healthy way to add fragrance to soap. Essential oil soaps are considered a healthy alternative because its oil is 100% extracted from plants like the popularized lavender and chamomile.

With all the health benefits of using essential oils in soap, you must be thinking that you can add as much as you want.

You actually have two options.

  • The first option is to follow the safety standards set by the IFRA, otherwise known as the International Fragrance Association.
  • The second option is to follow your personal preference in creating your own essential oil soap recipe.

Without further ado, the two factors explained in more detail may affect your essential oil soap-making process as follows:

Factor #1: IFRA Standards


In case you’re unfamiliar, IFRA is the international governing body that regulates the amount of essential oil that should be used in products like soap and perfume.

Over the years, they have developed standard essential oil usage rates that they deem safe for consumers.

Therefore, if you plan to market your essential oil soap, you must adhere to their global safety standards.

These standards or essential oil usage rates vary and depend on two sub-factors.

  • Brand of Essential Oil Used

Not all essential oils are made equally. This is because essential oils differ in potency and the allergens they contain.

This is why the IFRA came up with safety standards when people add essential oil to soap. They aim to prevent adverse reactions from essential oils, such as itching, rashes, swollen body parts, and redness.

Now, you must be wondering how to calculate the amount of essential oil to add to your soap. Well, the IFRA will give you the amount in percentage, depending on what essential oil brand you use.

  • A possible scenario is you have a pound of soap base with you, and the IFRA says that you should only use 3% of the essential oil from Brand A. The pound of soap in grams should be multiplied by this percentage, resulting in about 13.62g of essential oil to add.
  • After calculating the amount of essential oil to use, this is where the conversions step in. You should convert 13.62g as volume, which you can get by dividing the grams by 0.905 g/ml. The resulting value is 15.05 ml.
  • Once you know the amount of essential oil to add in its ml form, you should convert it to teaspoons by dividing the volume by 4.93 ml. By doing this, you arrive at a value of 2.5 teaspoons.

Therefore, with a 3% essential oil usage rate, the amount of essential oil to add is 2.5 teaspoons of fragrance oil per pound of soap.

  • Weight of the Soap


The weight of the soap will also affect how you convert the amount of essential oil you add to the soap.

You should use a volume measurement like ml when using a small amount of the soap base as a starting point to maintain accuracy.

Factor #2: Personal Preference

If you won’t be selling your essential oil soap, it is well and fine to do some experimenting on the amount of essential oil to add to your soap.

You can rely on essential oil to add to the cold process soap chart as a reference.

Recommended essential oils for soap making chart

Maximum Essential Oil Usage Rates Per Pound of Cold Process Soap

Essential Oil Max Usage Rate Weight of Essential Oil per Pound of Cold Process Soap (oz) Volume of Essential Oil Per Pound of Cold Process Soap (ml) Number of Teaspoons per Pound of Cold Process Soap
Lavender (40/42) 5% 0.8 23.7 4.8
Folded Lemon (5x, 10x) 5% 0.8 23.7 4.8
Bergamot (FCF) 4% 0.64 18.9 3.8
Cedarwood 4% 0.64 18.9 3.8
Coffee 3% 0.48 14.1 2.8
Eucalyptus 3% 0.48 14.1 2.8
Ylang-Ylang 2% 0.32 9.4 1.9
Basil (Sweet) 1.5% 0.24 7.0 1.4
Peru Balsam 0.9% 0.1 2.9 0.58
Clove Leaf 0.6% 0.09 2.6 0.52

You can adjust the amount recommended above by considering the two factors below when deciding how much essential oil to add based on preference.

  • The Potency of the Scent

With your method of choice, you can now experiment with the potency of the scent. Some people prefer a light and breezy scent, while others want that strong punch.

Remember, the more essential oil you add, the potency of the scent increases too. But, you should keep in mind that you also increase the likelihood of developing an adverse reaction due to the allergens in the oil.

  • How Long-Lasting the Scent Is

How long you would like the fragrance from the essential oil to last will affect the amount of essential oil to add.

You can have a more long-lasting fragrance to melt and pour soap than make the cold processed soap.



Q: How can I be sure that I won’t develop any allergic reaction to the essential oil in the soap?

A: Once you have concocted your soap formula, you should first test it out on your skin. Do a patch test by rubbing the soap on a small portion of your skin and letting it stay there for 48 hours.

If after 48 hours you don’t see any adverse reaction, you can continue safely using the essential oil soap.

Q: How do I know how much essential oil I should add to my soap base based on IFRA standards?

A: You may search online for the brand of the essential oil you’re using, and you will come across an IFRA compliance statement document for that specific brand.

You may also contact the company and ask for their IFRA compliance statement if they registered for one.

With this document on hand, all you have to do from there is search for category 9 and the percentage beside it.

Then, you can calculate the amount of that essential oil to use in your soap from there.

Q: Which oils work the best for soap making?

A: The best essential oils to work with for soap making are lavender, rosemary, folded lemon, and cedarwood essential oil.

These are the best oils to use based on versatility, cost, and availability.


When deciding how much essential oil you should add to soap, you should first identify your purpose. If you mean to sell essential oil soap, then you must comply with IFRA safety standards.

But, if you want the soap for yourself, you can be more flexible and generous on how much essential oil to add to soap. Just keep in mind that whether you decide to comply with the IFRA or are experimenting for personal use, safety is your number one priority.

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