Super-fatting Soap and Lye Calculators

by Elizabeth
(New Zealand)

I have a small batch soap recipe I would love to try out.

170 grams milk or water
56 grams lye
453 grams lard
15 mls essential oil

The recipe says I can substitute another oil for the lard. I would like to use olive oil.

I tried that lye calculator but I don't understand it yet.

It wanted to know what the super-fatting level is and I don't know this.

How do I get to know this? I guessed 8% and the lye came out the same. The olive oil level stayed the same but the liquid content is less.

Do I go by what the calculator said or by the recipe and will this ever make sense???

What is a good super-fatting level for bar soap?

I like a soap to lather up and I don't want to go leaping forth not really understanding what I am doing.

I hope this has all made sense to you.
Thanks again,


I've run the recipe you posted through SoapCalc and it looks like the super-fat is about 12 % which I consider a little high.

Standard recipes usually have a 5%-8% super-fat. Too much free oil in your soap will inhibit the lather considerably and too little will be drying.

If you want to make a single oil soap, here are the quantities of ingredients needed for a batch using 453 grams of olive oil.

Keep in mind that straight olive
oil soap does not have a big fluffy lather. The lather is quite thin and can be a bit slimy but it is super gentle on the skin.

Olive oil - 453 grams
Distilled water - 150 grams at 33% or 172 at 38%
Lye - 58.3 grams

The water is set at 33% and the super-fat is set to 5%.

I've given you a reduced water amount and a full water amount for the recipe since olive oil takes quite some time to come to trace. Using the reduced water will help it trace faster.

Recently, Anne-Marie posted on her website,, some single oil lather tests and she found that Pomace olive oil produced a nicer lather that regular olive oil when used on it's own. You may want to consider using it.

Visit SoapCalc's Directions and read them over. Use the recipe I've given you and plug in the numbers. Play around with it to see how it works. When using the calculator, you can click on the boxed numbers for help on those sections as well.

Also read up on my page about Soap Making Oils. Scroll down below the oils lists for information on what the different types of oils are and how to formulate a recipe.

You can also try some of the basic recipes that are already calculated out for you.

Hope this helps you out.

Good luck and keep at will make sense eventually!


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Using Lye Calculator
by: Liz Ellis

I have a question that I hope you can breath a big sigh of relief on and say - yippee you did it - so here is the question.

The last time I wrote to you - you suggested that I use the lye calculator - I have been trying - I want to make a simple castille soap in a very small mold I was given - it holds 360 g total - so I went to the lye calculator and tried it. This is what it gave me:

olive oil 239 grams
lye - 30.76 grams
water 90.82 grams
I also did it as 5% superfat - is that right for a good all round soap??

Is this right??? Will it work??? Have I understood what I have done and if not - what do I do to understand it better.

Also down the bottom of the recipe it says in the quality of my recipe that the cleansing is 0 and the bubbly is 0 - is this a problem - I so hope I am on my way to getting to grips with that lye calculator - I don't want it to be lurking round the corner laughing at my attempts to concur it.



You have used the lye calculator correctly! I put the amount of olive oil in soapcalc and came up with the same numbers as you.

5% superfat is perfectly fine for soap and the amount I most often use.

Olive oil on it's own does not have the cleansing qualities or a bubbly lather as per soapcalc. Don't worry though, the soap will still clean and will have a thin lather.

Many people make olive oil soap and love it.

Good luck,

Lye Substitute
by: Cathy

I'm afraid there is no substitute for lye in soap making.

Soap is the result of a chemical reaction between a lye solution and oil.

Without lye, you cannot make soap from scratch.

You can purchase pre-made soap in the form of melt and pour or soap for re-batching.

These forms of soap have already been made for you so that you can add all the 'extras' without having to work with lye.


No lye soap
by: Anonymous

What is the substitute for lye?

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