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How to Better Understand SoapCalc’s Soap Quality Numbers

A lot of soapmakers¬†start formulating on their own based on SoapCalc‘s soap quality¬†numbers, even though they are surrounded by mystery. Most soapmakers¬†aren’t exactly sure where the numbers come from or what exactly the numbers mean. So much so that students in my Formulating Soap Recipes class were blown away to learn what contributes to the numbers listed in SoapCalc.

Understanding SoapCalc's Quality Numbers

This article talks a lot about fatty acids. If you aren’t familiar with fatty acids in soapmaking, learn about what the major fatty acids in soapmaking¬†are and what they mean for your soap in this previous article.¬†I’ll include SoapCalc’s explanation for each quality below as well as diving into where the number comes from and what it really means for a soapmaker.

SoapCalc’s Soap Quality Numbers for Hardness

This refers to the hardness of the soap bar.¬† Higher is harder.¬† A range of 29 to 54 is satisfactory for this soap quality. (SoapCalc’s Definition for Hardness)

The hardness number in SoapCalc is deceptive for a number of reasons. Most soapmakers consider the hardness number as a rating of the physical hardness of the soap. While this is a good indicator of physical hardness, it’s not super¬†accurate! The physical hardness of a bar of soap is largely relative to the amount of water used in the formula as well as it’s curing time.

The hardness rating is calculated by adding all of the formula’s saturated fatty acids (lauric, myristic, palmitic, and stearic) together to create the rating you see. For example, in the case of castile soap (which is 100% olive oil) the hardness number is 17:

SoapCalc's Soap Quality Numbers for Olive Oil
SoapCalc’s Soap Quality numbers for Olive Oil, which contains very little saturated fatty acids.

Looking at olive oil’s fatty acid profile on the bottom left, you see that olive oil contains 0% lauric, 0% myristic, 14% palmitic, and 3% stearic. Add those saturated fatty acids up and you get 17% saturated fatty acids.

If you’ve ever made castile soap, you know that a fully cured bar of castile soap is actually very hard physically.¬†Saturated fatty acids do contribute physical hardness to a soap. But, almost any soap can become extremely physically hard after a sufficient curing period and reduction of the water amount in the soap formula.

I prefer to look at SoapCalc’s soap quality number for hardness as an indicator of how¬†durable or long lasting the soap will be after it’s cured. A soap formula with a lot of saturated fatty acids will last longer (under normal conditions) than a soap with lower saturated fatty acids. Of course, the type of water the soap is used in and how it’s used or stored will affect the soap’s durability.

SoapCalc’s Soap Quality Numbers for¬†Cleansing

This refers to the soap’s ability to grab¬†onto¬†oils.¬†[…]¬†Some soap molecules can have a very hungry oil grabbing end. ¬†Soap made with too much Lauric and/or Myristic Acid can irritate the skin by washing away not only the top dirty layer of oils, but also the protective layer of surface oils on the skin.¬† Generally speaking, keeping the total of coconut and palm kernel in your recipe to no more than 30-35% is considered the norm.¬† However, when using large or very large percentages of coconut and palm kernel the strong cleansing can be compensated for by¬†superfatting¬†with an oil or butter that has a high conditioning¬†value.¬† A typical range for Cleansing would be 12 to 22.¬†(SoapCalc’s Definition for Cleansing)

SoapCalc’s description for the cleansing number is pretty accurate. The description¬†should tip you off that the rating is calculated by adding together the formula’s lauric and myristic percentages together.¬†

Again, in the case of castile soap, you’ll notice that the cleansing rating is 0 because olive oil doesn’t contain lauric or myristic acid. Does this mean castile soap doesn’t¬†clean? Goodness no! It simply means that castile soap is less stripping than another soap formula. Castile soap still cleans by binding to dirt and oils and rinsing away.

Another important factor to consider (which is mentioned in SoapCalc’s definition) is that the cleansing rating does not take into account your superfat. The higher your superfat, the more free fatty acids there will be in the soap. The best way I can explain this in non-chemistry terms is to think of your superfat as a buffer, reducing the cleansing ability of the soap.

For instance, in 100% coconut oil soap, SoapCalc gives a cleansing rating of 67, which is far above the range of recommended cleansing. However, the recipe uses a 20% superfat to counteract the high lauric and myristic content of coconut oil. Coconut oil has an extremely long shelf life, so the high superfat isn’t going to cause issues with rancidity.

For most formulas, a superfat typically lies in the range of 3% to 7%, but it’s important to keep this in mind in relation to¬†the rating of cleansing in a formula. You want to consider the stability of your oils when changing up your superfat. If your formula is high in unsaturated fatty acids, you likely don’t want to go over 7% superfat.

SoapCalc’s Soap Quality Numbers for¬†Conditioning

Conditioning refers to the soap‚Äôs emollient content. ¬†A soap‚Äôs emollients are left on the skin. They help the skin ¬†retain moisture. ¬†They sooth the skin and keep it soft. ¬†A range of 44 to 69 is satisfactory for this soap quality. (SoapCalc’s Definition for Conditioning)

Like other rating numbers, the conditioning rating is calculated by simply adding up fatty acids from the formula! SoapCalc¬†adds¬†together the formula’s unsaturated fatty acids (oleic, linoleic, linolenic, ricinoleic)¬†to reach the conditioning value.

And while this is usually a good indication, as the unsaturated fatty acids are all responsible for conditioning in a soap formula, it’s not a great method to analyze the¬†formula’s overall conditioning. Not all fatty acids are equal in their contributions to soap formulas. For instance,¬†linoleic acid also contributes a silky lather feel and more conditioning in a small amount in comparison to oleic acid.

If a formula contains 30% oleic acid, 5% linoleic acid, 1% linolenic acid, 4% ricinoleic acid, it will feel more conditioning than a soap that contains 40% oleic acid and 0% of other other unsaturated fatty acids. But in SoapCalc’s eyes, the soap formulas will have the same conditioning rating of 40.

SoapCalc's Soap Quality Numbers for Tallow, which includes a nice spread of unsaturated fatty acids.
SoapCalc’s Soap Quality Numbers for Tallow, which includes a nice spread of unsaturated fatty acids.

Again, it’s important to keep in mind that because the ratings are determined by adding together fatty acids present. SoapCalc isn’t including your superfat in the numbers. No matter the soap formula, a soap with a 0% superfat will feel less conditioning than a soap formula with 10% superfat.

SoapCalc’s Soap Quality Numbers for¬†Bubbly Lather

This refers to the soap‚Äôs ability to lather up and get bubbly. ¬†A typical range of values would be 14 to 46. The higher Bubbly numbers will tend to produce a foamy, fluffy lather rather than a creamy lather with¬†little¬†or no bubbles. (SoapCalc’s Definition for Bubbly Lather)

And this is where SoapCalc’s Soap Quality numbers really starts to get pretty squirrelly. The rating for bubbly lather is calculated by adding together the lauric, myristic, and ricinoleic fatty acids.¬†While lauric and myristic acid are largely responsible for big¬†fluffy lather, ricinoleic acid does not actually contribute to the lather in the same way.

SoapCalc's Soap Quality Numbers for Castor Oil show how the lather ratings can be deceptive.
SoapCalc’s Soap Quality numbers for Castor Oil show how the lather ratings can be deceptive.

Ricinoleic acid is better viewed as a lather stabilizer, where it helps the lather longevity provided by the saturated fatty acids. Ricinoleic acid¬†in¬†soap¬†does not have a lot of lather on its own. I like to think of it as a great supporting actor rather than the¬†star of the show. If a formula contains very little lauric and myristic acid but a lot of ricinoleic acid, the bubbly rating will be really high. The formula won’t have the bubbly lather you expect from the rating given because the lauric and myristic are low on their own.

Personally, I simply subtract the ricinoleic content from the bubbly rating to reach a better idea of the size of the lather’s bubbles (big fluffy empty bubbles). In doing so, I’m basically adding the lauric and myristic acid content together, which is great because that’s the two fatty acids that contribute to that soap quality.

SoapCalc’s Soap Quality Numbers for¬†Creamy Lather

This value indicates the stability and creaminess of the lather. ¬†Usually, increasing Bubbly will decrease Creamy and vice versa. ¬†A range of 16 to 48 is common here. The higher Creamy numbers will tend to produce a creamy lather with lesser amounts of bubbles or foam. Soap made with oils that do not contain Lauric, Myristic or Ricinoleic acids will produce a soap with just creamy lather. An example would be 100% olive oil soap. (SoapCalc’s Definition for Creamy¬†Lather)

Just like with SoapCalc’s number for¬†bubbly lather, the creamy lather number is deceptive for the same reason. The creamy lather rating is calculated by adding together the palmitic, stearic, and ricinoleic acid content of the formula.

While the palmitic and stearic acid content is what is responsible for creamy lather, ricinoleic acid doesn’t actually contribute to the lather. As mentioned above, ricinoleic acid¬†is a lather stabilizer. Without palmitic or stearic acid, the creamy lather rating can be extremely high on account of ricinoleic acid but not actually produce a lot of creamy lather you would expect.

Like with the bubbly lather number,¬†I simply subtract the ricinoleic content from the creamy¬†rating to reach a better idea of the size of the lather’s bubbles (small tight creamy¬†bubbles). In doing so, I’m basically adding the palmitic¬†and stearic¬†acid content together, the two fatty acids that contribute to creamy lather.

Putting It All Together

Hopefully, you now have a better understanding of what SoapCalc’s Soap Quality numbers actually mean! SoapCalc recommends a range of ratings for each quality for a general purpose soap. These values are summed up below in this table:

Soap Quality Range
Hardness 29 to 54
Cleansing 12 to 22
Condition 44 to 69
Bubbly lather 14 to 46
Creamy lather 16 to 48

These ranges are great starting points for a soapmaker learning how to formulate.¬†By taking it a step further and understanding where the ranges are coming from and what contributes to them, you’ll have a better understanding of your formula.

SoapCalc's Soap Quality numbers of a standard beginner soap recipe.
SoapCalc’s Soap Quality numbers of a standard beginner soap recipe

The above formula is a tweaked version of the holy trinity formula that I like to use when teaching new soapmakers. As you can see, it fits into SoapCalc’s recommended ranges for soap qualities. I wouldn’t argue that it’s the best soap¬†recipe ever, but what each soapmaker likes and doesn’t like varies!

Personally, I prefer instead to formulate based on the fatty acid profile of the formula itself. For a general purpose body soap, I tend to follow these fatty acid ranges:

Fatty Acid Range
Lauric + Myristic 20 to 30
Palmitic + Stearic 20 to 30
Oleic 32 to 41
Linoleic 7 to 14
Linolenic 0 to 1
Ricinoleic 4 to 7

Most formulas that fall in these guidelines for fatty acids will also check out with SoapCalc’s Soap Quality numbers and their recommended ranges. The above¬†beginner soap formula comes pretty close to most of my fatty acid ranges as well.

Now, it’s important to note that what¬†the soap will be used for will largely influence the fatty acid ranges you aim for.

For instance, a soap for oily skin might have higher saturated fatty acids while a soap for dry skin might have more unsaturated fatty acids. In terms of SoapCalc’s Soap Quality numbers, this means that the soap for oily skin will have a higher cleansing number and a lower conditioning number. The dry skin formula will be opposite.

Shampoo bars might have higher ricinoleic acid content, so the SoapCalc numbers for lather will be hugely inflated. For shaving soaps that contain higher palmitic and stearic acid, the hardness and creamy numbers will look out of this world.

Keep in mind that variables outside of your fatty acids affect how your soap will perform, including the type of water it’s used in, how much of a superfat or water discount you use, how the soap is stored, how long the soap is cured, and so much more. SoapCalc’s Soap Quality numbers (and my own fatty acid ranges)¬†don’t account for all those extra variables! You, as a formulator, should understand and account for all those extra factors when formulating.

(Want to up your game when it comes to formulating? Snag our Formulating Soap Recipes class and create your perfect soap formula.)

SoapCalc’s Soap Quality numbers are great guidelines for a beginner soapmaker, and¬†they will serve you well when formulating. But it’s even better to understand how they are calculated and what to consider when using them as a formulating tool!

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54 Responses

  1. Hello Kenna, this is one more nice article that will help the soapmakers at the beginning of their formulating adventure.

    I just want to make a remark about the rancidity you mention and its relation with superfat. As Kevin Dunn has observed, the saponified fatty acids have the same pathogenesis with the non saponified ones, so superfat is not something that will show DOS faster. It will show it a little more intense though.

    Nikos

    1. Yes, I’ve read scientific opinions that go both ways. Personally, I recommend consulting your total linoleic + linolenic content for risk of DOS, so I guess I subscribe more to Dunn’s perspective than the other side.

      Thanks for commenting as always, Nikos!

  2. Bravo Kenna, Another excellent, informative article for those of us who want to make the best bar of soap possible. A wonderful refresher from the last fantastic workshop. Thank you

    1. Of course, Annie! I didn’t realize I was dropping such a big bomb in the workshop, so that’s why I wanted to share it here! ūüôā

  3. Wow! This is an awesome article. It really helped narrow down my understanding better. I know we are supposed to know the chemistry side of soapmaking, but it is one area that I do lack in. This helped by stating it in a way that even the chemistry bubbleheads, like me, can understand and apply to my formulas. Thank you for such a great reference!!!!

  4. Kenna,
    Thank you for this awesome break down! This information helps me a lot. My question is if adding a milk to the soap does it help for conditioning dry skin? I have used handmade soap years ago and it left my skin feeling sooo terribly dry! That’s why I always shied away of buying handmade soap. I want to create a soap that is moisturizing and leaves my skin more hydrated :-D. I am still a newbie but I really enjoy learning how to make a great moisturizing bar of soap and I love using milk! (ie)….
    coconut milk, oat milk, reg milk, etc…….
    Thanks for thd great aryicle!‚ô°

    1. It depends on who you ask. ūüėČ Some folks swear by milks (and when they do, they tend to swear by specific milks). I personally don’t see much of a difference besides the lather changes due to the sugars.

  5. Your amazing! Thank you so much for your blog! i am addicted to making my own soaps now. thank goodness i stumbled onto you. I plan on trying all different recipes! love it. thanks

  6. Nice article, however, one thing SoapCalc doesn’t address is solubility. A bar can be hard and fully cured yet still dissolve quickly in the bath. I wish that could be addressed somehow in these numbers.

    1. I look at the hardness number for this (it’s just the percentage of saturated fatty acids in the formula)! The lower the number, the faster it will likely dissolve and wear away. ūüôā

  7. Hey ho, Kenna! Ok. Love the article, too. I appreciated this because I never knew how the soap calc numbers were calculated, now I understand it better. But…

    What I still don’t get is this: what are the numbers? I thought, perhaps, it was the percentage of each fatty acid but I guess not.

    For example, in your castile soap example, we add together the palmitic and stearic, 13 + 4 = 17 and that is our hardness. Fine. But, if we add up all the numbers, 0+0+14+3+0+69+12+1 = 99. Ok, I thought.

    So, then I thought, maybe they are just a tad off. Try again. A 100% Coconut Oil Soap = 0+1+20+24+0+30+15+3 = 93. Oops. Must not be percentage of fatty acid composition then. Then trying the next example, a 100% Castor Oil Soap = 90 + 4 + 4 = 98.

    So, all this leaves me to figure that I don’t know what they are. What are they?

    1. Soap is not 100% the fatty acids listed, there are unsaponifiables as well as two other fatty acids we don’t tend to pay attention to. SoapCalc is just listing the percentage of a fatty acid in the formula, it’s not always going to equal 100%.

      There’s typically anywhere from 0% to 10% caprylic and capric acid in soap formulas. For instance, in 100% coconut oil soap, there is a combined total of 13% caprylic/capric. ūüôā

      SoapCalc also rounds their numbers, so that doesn’t help either. ūüôā

      I hope that helps!

  8. Another thought: do you have a fav range for the saturated fatty acids (long lasting bars of soaps)?

    I started out with very hard bars but have been lowering mine over time but still haven’t decided what I like best. Was wondering your preference on that variable.

    1. I personally tend to like formulas that are relatively high in saturated fatty acids, upwards of 65%, because I like a lot of stearic (creamy lather) and a really hard bar. These formulas tend to trace too quickly for newer soapmakers, so a lot of the tutorials here on Modern Soapmaking are lower. ūüôā

      1. Ok. I figured you used less since I think I got the idea from you recently (probably in the workshop) that since the hard bars last so long, we are smarter business wise to make them softer. What I do not like about mine is that they last soooooo long.

        As such, going to drop my saturated a tad and see what I think.

        1. My bars were much, much, much smaller than most soapmakers (3 oz), so they still lasted about the same amount of time as a larger bar that had more unsaturated fatty acids. Basically, you want a bar for sale to last between 2 and 4 weeks – whether that’s size, fatty acids, etc. ūüôā

  9. Wow, this is a great article. I have been making soap for close to three years and I was not getting it. I have read the SoapCalc artcle several times and used their calculator all this time. Some soaps came out ok in regards to lather but more times than not they were lacking. I make soap because I have very dry itchy skin in winter and my adult son has eczema so I make moisturizing formulas but the lather was not always there. Now I see why. I will definitely use your suggestion/idea of deducting the ricinoleic acid from the other two for a more accurate picture of both the bubbly and creamy lather. Also, small amounts of linoleic better than all oleic. Can’t wait to start formulating again. THANK YOU!

  10. Hi, Kenna. My question is about super fatting on soapcalc. Changing the % of superfat in my recipe does not affect my recipe’s properties (cleansing, bubbly, etc.). Can you explain why that is? It seems that changing the superfat content would drastically change the soap properties–making it less cleansing and bubbly and, probably, more conditioning or creamy as you raise the %.

    Thanks,
    Bonny

    1. Hey, Bonnie,
      You are right. Changes in your superfat are not reflected in SoapCalc’s property rankings. It one of the reasons we think the calculator is a great tool, but not the whole story.

      If you want to get a little more in-depth, Kenna’s formulating class is a great resource. Basically though, yes, you will need to remember that the higher the superfat, the lower the lather and cleansing. And the higher the conditioning.

  11. Hi Kenna. I love you article. It helped me understand what the Soapcalc numbers mean. I am so happy to learn how to make a soap for different skin conditions. I have a year making hot process soap. I always struggle adding the essential oils. because the hit evaporate the fragrance. I would love to know which temperature is the adequate to add the essential oils, as well as make the fragrance last longer in my soap. My goal is to make my soaps 100% natural. It will be nice if you can write a blog about this matter, or teach me how to do it. I really appreciate the time you took writing this blog and sharing it with us. Thank you very much.

  12. 1. Please let me know that is there any additives that can improve the conditioning of soap other than the list you mentioned? If i want to add Aloe Vera to my lye instead of water, what will be the proportion to add to it. If i add milk, is there any negative affect on soap? If no, please provide the proportion.
    2, How can i calculate the conditioning value with unsaturated fatty acids?
    3. How can i calculate the weight of the soap before making (Hot or Cold Process) OR if the total weight of oils & all are 10Kg before making, so how much it will be after making ?

    1. Ebin,
      1. Check out our Lather Lovers series for feedback on soaps made with aloe vera, various milks, and other additives.
      2. If you use Soap Calc, the software with add together your formula’s unsaturated fatty acids (oleic, linoleic, linolenic, ricinoleic) to reach the conditioning value.
      3. If you total the weight of all your ingredients and then subtract your water component, that is the approximate yield of your finished soap. A small amount of water will be retained after cure, and there will be a small amount of waste left in your mixing container and on your utensils.

      Hope that helps, Ebin.

  13. This article is SO helpful. Is there a chart out there that shows SoapCalc’s number for each of the fatty acids, by type of oil? It seems like someone should have done that work already.

  14. Thanks for your most informative article which has cleared all about qualies and fatty acids range and numbering thereof. Kindly help me to know about the Sat:Unsat ratio It. Can you kindly explain it.

  15. I’m new to soapmaking and trying to formulate a shampoo bar. Do you have a fatty range I could use to base my values on? Like a general purpose shampoo bar?

  16. Thank you very much. This was very helpful since it aided in me making sense of some of my soaping observations.

  17. Hi STEPHANIE, just want to know where I may lear how to calculate the Soap Qualities numbers, hardness, cleansing… (i mean with pencil and paper not with online calculators).

    Thanks in advance

  18. You mentioned above that soapcalc ignores some fatty acids.
    What characteristics are in capric, caprylic and palmitoleic acids that might affect SAP, and the qualities (hardness, cleansing, conditioning, bubbly, creamy)? Are these ignored because they really have no effects on either the lye calculations or the qualities?

    1. Hey, David,
      Typically those fatty acids are in such low quantities that they don’t affect the soap qualities. They perform similarly to lauric and palmitic but are generally more conditioning.

  19. Hmm this article makes me want to make 6oz bars of 100% oils just so I can get a feel for them. Might be a project to put together.

  20. I have both coconut oil-76 deg and fractionated coconut oil. the fatty acid profiles are practically non existent in soapcalc but it still gives properties bubbly, cleansing and hardness at 100% with everything else at 0. Soapmaking friend shows this as well. If Lauric acid is what makes the soap have big bubbly lathers in hard bars, how is it possible that fractionated coconut oil with a lauric count of 2 shows this?

    1. Caprylic acid (C8) and capric acid (C10) are the two main fatty acids present in fractionated coconut oil. Those aren’t included in SoapCalc’s calculations, which skews the numbers.

  21. I see you speak of this “simple holy trinity formula”, but I don’t see it anywhere on your site or a link. Could you please provide a link for that? I am interested in seeing it .

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