Skip to main content

The Ultimate Soap Recipe!

Sharon has been making and selling soaps and personal care products for about five years.

Orange Clove Soap, Made with Soap #3 Recipe

Orange Clove Soap, Made with Soap #3 Recipe

Soap from oval molds, scented with China Rain

Soap from oval molds, scented with China Rain

Orange scented soap

Orange scented soap

Looking for a Really Great Soap Recipe?

Here are a few soap recipes—some good, some not so good—presented along with my thinking about what makes a soap good. These recipes are also presented to illustrate how to develop a good soap formula.

These are just my opinions, though. Soapmaking is an art, so no one's opinion really counts for all that much—maybe least of all mine, since I have only been making soap for less than two years. But I am a recipe nerd! Fine-tuning soap qualities became my soaping "mission" early on.

I've given recipes for four soaps, beginning with the lackluster Soap #1. Most of the pictures are of the Soap #3 Recipe because this is the recipe that I've been happy to use for nearly a year. Soap #3 (again, in my opinion) is an excellent recipe, but I think the Soap #4 Recipe is better.

Here's the story of the evolution of a recipe.

Like most beginning soapmakers, my soapy adventures began with recipes I found online. I think this is a perfectly reasonable starting point.

Some experienced soapmakers become highly offended when beginners ask for a soap recipe. This is because, after months or years of experimentation, which cost them many hours toiling over crock pots and sweating bullets to understand lye calculators—not to mention quite a few bucks—they achieved the perfect bar of soap.

They began with a fairly simple recipe and produced many variations of it, each of which was critically evaluated—often by a small army of friends and relatives acting as testers. If The Recipe was tested and found wanting in some desirable quality, the soapmaker began another round of experimentation. So beginners who go online requesting recipes are often told to figure it out on their own—when they are not actually suspected of industrial espionage.

Anyone can make soap. You can make soap with lard, as our foremothers did. You can make soap with coconut oil, olive oil, palm oil, or any of the other oils on the grocery shelves. Some of these oils will make a perfectly serviceable soap all by themselves. (Some will not.)

And a soap made only with lard, coconut, olive, or palm oil—while it may have some defects—will beat the pants off of the detergent bars (called "beauty bars") that you will find over in another aisle at the grocery store. They'll beat the pants off of them because they are soap rather than a mixture of detergents and chemicals, which also usually contain a cheap synthetic fragrance to mask the subtle unpleasant scent of these concoctions.

Even a simple soap is much kinder to the skin than most commercial "detergent bars."

But beginning soapers who have a little experience under their belts, and have learned that they can definitely make soap, often want to take it to the next level. They'd like to make really great soap.

Coconut-Mango Soap

Coconut-Mango Soap

Scroll to Continue

Read More From Feltmagnet

What Makes a Great Soap Great?

What exactly is a really great soap?

A really great soap would be a soap that makes a decently hard bar that produces a long-lasting lather that is a balance of bubbly and creamy. It should feel wonderful on the skin, not strip the skin's natural oils, and contain enough superfat to replenish any skin oils that are washed away.

Further, the oils in the superfat (and the soap itself) should be the most desirable kind in terms of skin benefits. While you can only accomplish this last with certainty by making hot-process soap—which allows you to choose your superfat—you can do this in cold-process soap to an extent, simply because the most desirable fatty acids in soaping oils are the slowest to saponify. So, for cold process, you just have to make sure that those "most desirable" fatty acids are included in your recipe in a reasonable amount.

The bar of soap should have a pleasing texture, both visually and to the touch—sort of silky and creamy. The recipe should perform well, meaning you should be able to depend on it to remain fluid during pouring and swirling. (No formula will do this every time since fragrances can cause acceleration—sometimes called "soap on a stick.")

While I suppose it is obvious that a great bar of soap should do a good job of cleansing, it is hard for me to imagine any soap formula that would strike out in that department. Usually, a soapmaker's main concern is to formulate a soap that isn't overly cleansing.

There are probably an infinite number of possible formulations for a truly great soap. It is an article of faith among soapers that every soaper's unique experimental journey leads them ultimately to a unique formulation of the "truly great soap."

One reason this is an article of faith is because not just everyone will tell you their soap formula.

Hint: The ingredients are usually on the label, and anyone with a fair understanding of soap qualities can run these ingredients through SoapCalc, or some other online lye calculator and figure out how these ingredients can be optimally balanced. This experiment may reveal that someone else's "secret recipe" is actually not all that great. Many of the "real" soaps on the shelves at health food stores are, from the standpoint of artisan soapmakers, rather ho-hum—because making a decent soap for selling wholesale at a reasonable price has its own special set of constraints.

It takes a certain amount of experience at soapmaking to recognize a good bar when you see one—or try one. This is partly because the simplest real bar of soap beats the pants off of commercial detergent bars and is so delightful to use that it can be hard to believe you haven't achieved the Ultimate Recipe right out of the gate. I mean, how could it get any better? I made the same basic coconut oil soap recipe over and over for about six months before I was ready to move on.

As you try different recipes, and different variations of the same recipe, you steadily become more discerning. You can feel the difference between a 5% superfat and an 8% superfat, and the difference between a soap with linoleic acid and a soap without it. You've seen enough different kinds of lather to recognize good lather, and you've critically evaluated the appearance enough bars to recognize that silky, creamy look.

The question is, how do you achieve all this?



Other Lye Calculators

You may want to have a look at other online lye calculators.

Here is the link to the MMS lye calculator:

Here is the link to Brambleberry's lye calculator, if you'd like to have a look at it:

If you look at Brambleberry's lye calculator, you can see that it is very straightforward; just fill in the blanks. To choose a superfat level—at the very bottom of this page—beginners should usually choose 5%. If you compare this page to the SoapCalc page, you will notice that on the SoapCalc page, 5% superfat is the default.

There is a very good reason for this: While all the oils you could use to make soap have a SAP value—which allows the amount of lye necessary to saponify that particular oil to be calculated in the real world, the SAP values of oils can vary due to weather and other growing conditions.

SAP values for all oils are, hence, averages. It is possible that the oils you are using do not have the average SAP value. There is no way to know unless you have access to a lab. Your oils might require more—or less—lye than the average needed. If they require less lye than the average, and you calculated your recipe for 0% superfat, your finished soap could have excess lye in it.

Excess lye makes soap harsh and can burn the skin. For this reason, it is the standard practice to calculate for at least 5% superfat—superfat being the amount of fats/oils that are left over after saponification. This minimum amount of superfat ensures that there won't be any excess lye in your finished soap.

On Brambleberry's lye calculator, beginning soap makers will usually choose 5% superfat. Brambleberry's calculator only goes up to 10% superfat. While this is plenty for most recipes, sometimes you need a higher superfat than this.

Now look at SoapCalc's lye calculator. Superfat is number 4 at the top of the page. SoapCalc will allow you to choose a higher superfat percentage than Brambleberry. If you click on the number 4, SoapCalc will supply an explanation for what is meant by superfatting.

With the Brambleberry lye calculator, you simply fill in the blanks and click "Calculate." The calculator will then tell you how much lye and how much liquid (usually water) to use to make soap. This is fine if that's all you want to know.

The MMS lye calculator is useful if you want to know how much sodium lactate to add to a recipe, and it also allows you to calculate a recipe using dual lyes (both NaOH and KOH).

Each of these lye calculators is useful in its own way, but if you want to use a lye calculator to gain an insight into soap qualities, SoapCalc is preferred.

Use the Tools

Luckily, there is no need to flail around in the dark about this. These questions have readily accessible answers. To find out these answers, your first stop should be to familiarize yourself with SoapCalc. SoapCalc is one of many online lye calculators. Here is the link:

SoapCalc can seem a little overwhelming at first, and some people prefer a simpler lye calculator, such as the one at the website or the MMS lye calculator at Majestic Mountain Sage. Many people prefer them; I prefer SoapCalc.

Looking at numbers 1, 2, and 3 in SoapCalc, notice that the default for 1 is NaOH, which is what you use to make bar soap. Click on the box with the 1 in it, and it will explain this. The number 2 allows you to choose your unit of measurement. If you are in the US, you will probably choose "ounces."

If you are just about anywhere else, you will probably choose "grams." If you click on the number 3 in the box, SoapCalc will explain why their default for "Water as a Percent of Oils" is set at 38%. Beginners will normally want to leave this set at 38%.

Notice that if you click on one of the oils in the "Oils, Fats and Waxes" list, SoapCalc gives you a column of numbers under "One." These numbers indicate the qualities you could expect in a soap made from this one oil alone. If you double-click on an oil, the calculator will put this oil into the "Recipe Oil List"—your recipe. If you double-click on more oils and add them to your "Recipe Oil List," the calculator will give you numbers that represent the soap qualities of this combination of oils in the "All" column.

Now put a few oils into the "Recipe Oil List" and look at the numbers in the "All" column. If you hover over Hardness, Cleansing, Condition, Bubbly, Creamy, Iodine, and INS, the calculator will tell you the recommended range of numbers for each of these qualities, and you can check your numbers for each quality to see how your (for now "pretend") recipe measures up.

The best way to get familiar with SoapCalc is to play with it. Use it to evaluate your current recipes, some online recipes or recipes from books, some recipes you have in contemplation, etc. One thing you'll notice is that there is a great deal of elasticity, as far as what you can and can't (or should and shouldn't) do when formulating a recipe. As one of my former employers put it, "De sky is de limit!" (Riiiight.)

While there is no substitute for experience—and lots of it—SoapCalc provides an evaluation of the qualities of just about any soap recipe you can dream up, and it provides a recommended numerical range that beginning soapmakers, especially, may want to heed. Or maybe not. You can learn a lot from "pushing the envelope."

Honey Patchouli Soap, Made with Soap #3 Recipe

Honey Patchouli Soap, Made with Soap #3 Recipe

What Qualities Do Experienced Soapmakers Prefer in Soap?

It is probably presumptuous of me to claim to know what "experienced soapmakers prefer." There are probably many who don't prefer what I prefer, and don't prefer what I think they prefer, so you may want to know where I'm getting these notions. They are drawn mostly from the comments and discussions among soapmakers in the many soapmaking groups, mostly on Facebook—though some are drawn from soapmaking forums.

The best way to find out the views of experienced soapmakers is to join several of the soapmaking groups on Facebook, where thousands of soapmakers offer their opinions about everthing soap-related, answer questions, and help troubleshoot problems. Members also offer lots of inspiring pictures!

I think we can assume that the "experienced soapmaker" prefers (and can make) a soap that has all the good qualities I mentioned earlier, but their preferences will be more fine-tuned. There seems to be a very strong tendency to shoot for very skin-conditioning, "moisturizing" recipes. In terms of SoapCalc numbers, this usually means a high Condition number, a low Cleansing number, and a moderately high superfat percentage.

Perhaps unsurprisingly, experienced soapmakers do not always agree with SoapCalc's guidelines. Some soapmakers make 100% olive oil soap (Castile), or 80% olive oil soap (Bastile) with a merry disregard for the way these formulas are WAY outside all but one of SoapCalc's recommended numerical ranges. Olive oil is nearly unique among unsaturated oils when it comes to producing a very hard and very fine bar of soap when properly cured. SoapCalc does not reflect that.


Unless you are making a Castile or Bastile soap, it is easy stay within SoapCalc's recommended Hardness range without compromising other soap qualities. At the lower end of this range—and even towards the middle of the range—you may want to add hardeners to your formula. Hardness can be increased by adding salt or sodium lactate.

Sodium lactate is preferable for this purpose because salt has an adverse effect on lather, and sodium lactate helps lather, at least a little. High amounts of salt will also bleach out many soap colors, and sodium lactate will not. Sodium lactate is very beneficial to skin, as well, and works almost twice as well as glycerin as a humectant.

I feel that sodium lactate is almost essential if your goal is to make a high conditioning soap with an acceptable hardness. You can use the MMS lye calculator to give you recommendations on the amount of sodium lactate to add to your specific recipe:


Most soapmakers prefer a very low Cleansing number. Almost all soapmakers insist on a number below 15. Some insist on a Cleansing number no higher than 12, and some insist on a Cleansing number somewhere between 0 and 12. I think a Cleansing number of 12 is satisfactory, but lower is in many ways better—if you can do this and still get the texture and other qualities you want.

"Pushing the envelope" on your Cleansing number also risks formulating a soap with poor lather, but there are additives that will compensate for this problem, too. The easiest approach is to just add sugar to your recipe, up to a tablespoon per pound of oils. Adding milk, honey, beer, or any other liquid containing sugars will also work. Substituting apple cider vinegar for all water helps, especially if you also add sugar. Sodium lactate is said to improve lather.


What does SoapCalc mean by "Condition"? Here is the page with their explanation of soap qualities: What it says about their Condition number is this: "Condition - Conditioning refers to the soap’s emollient content. A soap’s 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."

Most soapmakers like their soap to have a Condition number at the high end of the recommended range. A high Condition number indicates a soap that is gentle to the skin. Most people (though not all) seem to prefer the feel of high-conditioning soaps, and many soapmakers were first drawn to making their own soap because of issues with dry, sensitive skin, or because they wanted to help the skin problems of their children, friends, or relatives.

As with other soap qualities, you can only push the Condition number so high without compromising other desirable qualities—most often hardness and lather. When your recipe gets into the higher range on its Condition number, you are likely to need to add hardeners like salt or sodium lactate, as well as additives that boost lather, like sugar, honey, beer, or milks of some kind.

These additives will only work up to a point, and how well they work can vary with each recipe, so the only way to learn how high you can push the Condition number without compromising other desirable qualities is through experimentation. Plus, of course, different people will have different preferences, and your preferences as a soapmaker will evolve.

It is always a good idea to set aside a bar—or at least an end piece—of each batch of soap you make, to see how it performs over time. This is especially true whenever you venture outside SoapCalc's recommended ranges. You can watch for DOS and notice changes in appearance like cracks and discoloration.

I think a Condition number of 58 is high enough—though I would like to push it to 60 or above where possible. I have a few bars of a batch of soap that I made over a year ago, made with 50% sunflower oils and a Condition number of 72 . People who were gifted with bars liked it very much. I didn't care much for its appearance (it has an unappealing translucency), but I like its performance. It was also a little on the soft side since I added no hardeners. Lather was good because of the addition of honey. Some bars got DOS after 6–9 months, and some bars still show no sign of DOS after more than a year.

My final verdict on this soap: This may be a very promising recipe that could be developed into a truly great soap with a few tweaks.

I guess the bottom line on the Condition number is that you must work out your preferences through experimentation.

Lather (Bubbly/Creamy)

Good lather is a must in hand-crafted soaps if you want people to like them. Most soapers rely primarily on coconut oil to provide bubbliness to lather, with the caveat that a soap with more than 20% coconut, unless with a very high superfat, will be too cleansing for most people's tastes, and can feel harsh. Palm and tallow provide creaminess. But again, if you load your soap up with oils that produce abundant lather, other soap qualities will likely suffer.

I think the best approach to getting good lather is to make a high-conditioning, low-cleansing soap and don't fret too much if lather is at the low end of SoapCalc's recommended range on Bubbly/Creamy. Just add sugar, honey, beer, or milk for lather. These do a great job! Sugar is excellent for boosting lather, and if you have tried adding one talespoon of sugar per pound of oil to your recipe and you still think the lather is lackluster, you can always add more. Try adding 2 tablespoons per pound of oil.

The lather of most soaps improves over time. My experimental soap with 50% sunflower oil and a Condition number of 72 has a Bubbly number of only 6, but the lather is, if not lush, pretty good, because of the addition of honey.

Lather is another area where tastes and opinions vary. Some people will not be satisfied with lather until it explodes all over the tub. Others just want enough lather to feel assured the bar they are using is really soap.

Some other things that help at least marginally with lather are subbing ACV for all water and adding sodium lactate.

Salt added to soap for hardness will decrease lather. This is why salt soaps are made with a very high percentage of coconut oil—the only oil that will make a soap that lathers in the presence of high amounts of salt. Sodium lactate will harden soap without diminishing lather, and in fact, is said to boost it.

Iodine and INS

I am not even going to try to explain what these numbers really mean.

Frankly, they remain largely a mystery to me. I have made lovely soaps that were seriously outside the recommended limits on both Iodine and INS. I have also made soaps outside these limits that were too soft. My general impression is that you can risk ignoring these numbers if your soap's Hardness number is high enough. Be aware that sometimes it works and sometimes it doesn't.

Again, using my 50% sunflower oil soap with a Condition number of 72 as an example, Iodine is 98 and INS is 97—wildly outside recommended ranges. (It was an experiment, okay?) It is in many ways a pretty good soap. As with all else soapy, experience and experimentation is your friend. Many of these "not quite right" recipes can be the springboard to developing the Perfect Recipe.

Lavender Soap

Lavender Soap

Fatty Acid Profiles in Soap

If you look further down the "Soap Qualities" column, you will see that SoapCalc also gives numbers for each of eight fatty acids. These numbers are the percentage of these fatty acids in single oils (in column one) and the combination of oils in your recipe (column two). These numbers are very meaningful in terms of the properties of your finished soap. If you are a beginning soap-maker, you will want to learn as much as you can about the properties of the various fatty acids.

Here is one link that explains this, along with some of the special qualities of some of the fats, oils, waxes, and butters you might use for soap-making:

The more experienced you become in making soap, the more breathless your interest in the fatty acid profiles of different formulations of soap.

One of the reasons that each soapmaker's Perfect Recipe is unique is because preferences as to fatty acid profiles of soap are variable. People with dry and sensitive skin can have a strong dislike for high percentages lauric and myrsitic acids in soap, and some don't care much for a high percentage of palmitic acid.

Recipe nerds like myself have a keen interest in the fatty acid balance of a recipe and will tend to prefer soaps that are lower in lauric, myrsitic, and palmitic acids, and higher in oleic. They often like linoleic and linolenic acid percentages to be as high as possible without excessive risk of DOS (dreaded orange spots caused by the superfat oils in soaps becoming rancid).

I don't have a clear opinion on the ideal percentage of stearic acid in soap, due to lack of experience and attention to this one, but I'm starting to notice that something like 10–12% is very nice.

This link on The Most Popular Fatty Acid Profiles in Soapmaking may help provide some clarity:


Superfat in soap is the percentage of unsaponified oils that are left in the soap after saponification is complete. Since soap is created through a chemical reaction between lye (a base) and fatty acids (weak acids in fats and oils), you may remember from Chemistry 101 that X amount of a base will only "use up" X amount of an acid. Because electrons. Once the lye in your recipe has reacted with the fatty acids in your recipe, it's just . . . gone. It's not there anymore. Any oils that are still around after the lye is gone are called superfat.

If you set your superfat to 0% in SoapCalc, it will give you a lye amount that (theoretically) will use up all the fatty acids in your recipe, so that there is are no oils still around after saponification is complete.

This is not desirable. This is because the SAP values of oils used in lye calculators are averages. The real SAP values of the oils you're are using are unknown. (Creepy, right?) These variations in SAP values are caused mainly by growing conditions of the animal or vegetable fats the oils come from.

Maybe the real SAP values of your oils are higher, or maybe they are lower than the averages used by lye calculators. If you happen to be using fats and oils that have a lower SAP value than the number used by your lye calculator, there will be leftover lye in your soap. This is not good. A lye-heavy soap will be harsh and can irritate or even burn skin.

This is why lye calculators have a default superfat setting of 5%—meaning the lye calculator will give you a lye amount for your recipe that will (theoretically) leave 5% of the fatty acids in your soap unsaponified. On the other hand, if the SAP values in your fats/oils chances to be on the low side, a 5% superfat ensures that all the lye in the recipe will be used up, by throwing in a little extra fat just in case.

While soaps made for special purposes, such as laundry soap, are usually made with a 0% superfat, body soaps should always be made with at least a 5% superfat. Body soaps made with very high amounts of coconut oil, on the other hand, are normally made with at least a 20% superfat. (Some people go higher than 20% for these soaps.)

Okay, so what's NORMAL in the way of superfat? Again, conjuring the spirits of "experienced soapmakers," the preference seems to be for 7%–8% superfat. I use 8%. Some people in the soapmakers' groups on Facebook speak of using 10% superfat in their body soaps. I have never tried going up to 10% superfat, so I can't comment on this.

Once again, experimentation is your friend. Much depends on personal preference and probably also on the way The Recipe is formulated. Much also depends on whether you have hard or soft water.

Elderflower scented soap

Elderflower scented soap

Sat : Unsat Ratio

You will see the Sat : Unsat Ratio near the bottom of the SoapCalc's lye calculator page, right under the fatty acids column. On the View/Print Recipe page, it is shown at the very top right of the page. This is the ratio of saturated fats to unsaturated fats in the recipe. Looking at it another way, it is the ratio of hard oils to soft oils. The most commonly recommended Sat : Unsat ratio is 60:40—that is, 60% hard oils to 40% soft oils.

Many soapers prefer a 40:60 Sat : Unsat ratio. This is because the soft oils are the more conditioning oils, richer in what I would call the "nutrient" oils: oleic, ricinoleic, linoleic, and linolenic. In my view, anything in between the 40:60 and 60:40 is good, but if you want a soap with a high Condition number, you will almost certainly wind up with something more like a 40:60 ratio. The lower the percentage of saturated fats, the more likely you will need to add sodium lactate to your recipe for hardness.

Soap #1 has a 36:64 ratio, which made its hardness marginal.
Soap #2 has a 38:62 ratio. It is, in my opinion, a fine recipe with the addition of sodium lactate for hardness.
Soap #3 is right at 40:60 (though this is cut off in the screenshot). With the addition of sodium lactate, it is darned near perfect.
Soap #4 is also right at 40:60 and, in my opinion—with the addition of sodium lactate—is the best of all.

Here again, no one can tell you what to do on this ratio, as it will depend on personal preferences.

You may notice that health-food-store "real" soaps are quite hard. My impression is that soapmakers who sell a large volume of soaps wholesale feel the need to produce a very hard soap—probably harder than 60:40—because their soaps will need to stand up to shipment and handling