Soapy Math: Convert Essential Oil Blend Recipes for Soap

I confess to not being very adventurous when it comes to creating new essential oil blends.  I've read the posts about top, middle, and base notes and have found lists of what essential oils blend with others.  But when faced with a row of possibilities in those glass jars, I don't have that "this is going to be fun!" attitude.  Instead I'm overwhelmed and uncertainty rises to the surface.  I think that I can't put a good blend together because my favorite scents are never the ones that other people like.  I can't see throughthe forest to see that is exactly why I will be good at putting a blend that suits only me.  More than likely I will turn towards Pinterest for inspiration and examples to get me started.

 When it comes to looking for ideas for essential oil blends, there are many suggestions especially for diffusers or therapeutic blends.

The recipes normally look something like this:

• 20 drops Peppermint• 15 drops Eucalyptus• 15 drops Lavender• 15 drops Frankinscense.png


The problem is that my soap recipe looks like this:

·         1.5 oz fragrance

Am I the only person who doesn't know how many drops are in an ounce?  I've run across some recipes that say 100 drops.   I'm telling you right now, I am certain that I will lose count and that some drops will come in uncountable blobs.  All of this makes me want to shout, "I refuse to count drops when I make soap!"  Fortunately, I am able to convert drops to ounces without ever knowing how many drops are in an ounce.

How do you convert a recipe measured in drops into amounts that you can use in soap making?

It is a two step process:

1.  Convert the essential oil blend recipe to percentages

2.  Convert the essential oil percentages into the amount needed for your specific soap recipe.


Step 1:  Convert  essential oil blend recipe to percentages

1.       Add together the number of drops to get the total number of drops in the recipe.

Using our example above, 65 is our total number of drops.

20 drops Peppermint + 15 drops Eucalyptus + 15 drops Lavender + 15 drops Frankinscense = 65 drops

2.       Once you know that total number of drops, you then calculate the percentage each essential oil as part of the total amount.  To do this, take the number of drops for the specific oil and divide it by total number of drops.  To turn this number into a percentage you would then multiply that number by 100 and then round your answer to the nearest whole number.

# of drops of individual oil      x 100

total # of drops in the blend

Peppermint (20 drops):                  20 / 65 * 100 = 31%

Eucalyptus (15 drops):                   15 / 65 * 100 =  23%

Lavender (15 drops):                      15 / 65 * 100 =  23%

Frankinscense(15 drops):           15 / 65 * 100 =  23%

In your recipe file, you will want to store the recipe blend in a percentages formula so that you can reuse it on any size of soap batch.

• 20 drops Peppermint• 15 drops Eucalyptus• 15 drops Lavender• 15 drops Frankinscense (1).png


Now you are ready to apply those percentages to your soap recipe. 

STEP 2: Convert the essential oil percentages into the amount needed for your specific soap recipe.

To calculate how much you will need of each essential oil, multiply the percentage times the total amount needed.  Repeat this for every oil in your blend.

                Essential Oil % x Recipe Amount = Essential Oil Amount

In our example above our soap recipe calls for 1.5 oz of fragrance oil.  We will multiple 1.5 times the essential oil percentage to calculate the amount for each essential oil needed to scent our soap.

Peppermint:                      31% * 1.5 = .47 oz

Eucalyptus:                         23% * 1.5 = .35 oz

Lavender:                            23% * 1.5 = .35 oz

Frankinscense:                  23% * 1.5 = .35 oz


Soaper Beware:

What does an essential oil blend found on the internetNOT tell you?

How much of an essential oil can safely be used in soap?

There is no one answer to this question.  Generally speaking, the standard usage rate for fragrances in soap, a wash-off product, is between .4- .8 ounces per pound of oils (PPO). I often start at .5 oz PPO and adjust as needed for scents that are overly strong or others that fade quickly.  However, each essential oil also has its own individual guidelines that take into account its capacity to cause skin irritation, sensitization or photosensivity.  The recommended usage rate of certain essential oils may be much lower than other essential oils.  Spicy essential oils such as cinnamon or clove are examples of essential oils that are used in lower amounts to limit irritation.

There are a few places to get the usage information for essential oils:

·         IFRA Standards and Code of Conduct -                                                                                              

o  The IFRA Code of Practice and the IFRA Standards Booklet are available on IFRA’s website:  IFRA is the globally accepted system for the safe use of fragrance ingredients in specific product types

o   However, IFRA does not give the percentages per essential orange but lists it per constituent.  This means soap makers must know the constituents that make up each essential oil blend to determine what the safe amounts are.

·         Suppliers websites - I selected three suppliers that are popular with soap makers

o   New Direction Aromatics - New Directions had a wealth of information about each essential oil, including the main constituents.  This will make it possible to find the safe use percentages from IFRA.  They do not include on their website a usage percentage specific to soap or wash off products so it will be necessary to do more work before determining if your desired percentage is safe.

o   Brambleberry - Each essential oil product listing does contain warnings but does not include usage percentages.  They do, however, have a fragrance calculator that takes into account the usage rates and product type when displaying the different scent strengths.  With the information on their website, you can determine if your amount is under the maximum usage rate.

o   Wholesale Supplies Plus - WSP includes the IFRA % for each product type.   Usage rates are very accessible to the soap maker.

To get you started I've included 7 additional blends for you to try.


25% Lavender

25% Grapefruit

25% Lemon

25% Spearmint


Fresh Air Blend

33% Tea Tree

33% Lime

34% Lemon



32% Tangerine

32% Orange

18% Patchouli

13% Ylang Ylang

5% Chamomile


Citrus Woods

50% drops Wild Orange

30% drops Lime

20% drops White Fir


Lavender Woods

42% Peppermint

25% Lavender

33% Cedarwood


Fresh Mint

45% drops Grapefruit

33% drops Peppermint

22% drops Clary Sage

Sleepy Hippy

40% Patchouli

40% Lavender

20% Vetiver