# Using a lye calculator



## Mandy (Dec 12, 2006)

*Using a lye calculator*

Source: http://www.suite101.com/lesson.cfm/17779/1067/4

What is a lye calculator?

A lye calculator allows you to develop and test your own recipes by telling you how much lye to use with the oils you have selected. You can also use a lye calculator to doublecheck a recipe you have selected from a book or the web before using it.

Why is it necessary?

Different oils have different amounts of fatty acids and unsaponifiable material. That means that different amounts of lye are required to produce saponification. The lye calculator will allow you to determine the correct amount of lye for your recipe.

How do I use the lye calculator?

Write out a list of oils you intend to use in your soap and the amounts (in ounces) you intend to use (Step 1 in the example below). Now multiply the number of ounces being used by the sap value of the oil (see Step 2). Total your list of figures to get the total amount of lye necessary to saponify your soap (Step 3). However, most soapmakers prefer to automatically superfat their soap by 5%. This is done by reducing the lye by 5% - also called discounting the lye (Step 4). Now calculate the amount of water needed for the recipe by dividing the total ounces of oils used by 3 (Step 5).

Example

Here is an example of the lye calculator in action with my super duper moisturizing bar for very dry skin. Feel free to use this recipe, for personal use.

Step I Castor Oil 2 oz
Cocoa Butter 2 oz
Coconut Oil 4 oz
Olive Oil 6 oz
Palm Oil 6 oz
Avocado Oil 3 oz
Apricot Kernel Oil 2 oz

Step 2 Castor Oil 2 x .1286 = .2572
Cocoa Butter 2 x .137 = .274
Coconut Oil 4 x .190 = .76
Olive Oil 6 x .134 = .804
Palm Oil 6 x .141 = 0.846
Avocado Oil 3 x .133 = .399
Apricot Kernel Oil 2 x .135 = .27

Step 3 3.6 ounces lye necessary to saponify the soap.

Step 4 3.6 x .95 = 3.4 ounces lye

Step 5 25 ounces oil divided by 3 = 8.3 ounces water.

Things to remember:

    * Double, even triple check your calculations.

    * Lye calculators which automatically calculate lye and water for you can be found on the web.


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## susucosp (Oct 10, 2011)

i was study engineering 26 years ago. i am a newbie in soap making. i just make my first batch of 100% olive oil 4 days ago after 1 weeks of reading on the internet and in youtube.com.   i check the lye calculator in this forum want to know how much lye i need, but there are so many questions i do not know.  it is really confusing.  your example is really simple. 

i read on the internet and i creat my own oil formula and i want to try to make a batch.

can you help me list out like the example what you have done for the lye and water i need?  no superfat!
2 oz	carrot oil
4 oz	olive oil
4 oz	castor oil
1 oz	wheat germ oil
2 oz	sesame seed oil
1 oz	rose hip oil
4 oz	kukui nut oil
2 oz	jojoba oil

thanks

can you recommend the most simple lye calculator so that i can just type in my ingredient and and weight and then come out to what i need lye and water?





> *Using a lye calculator*
> 
> Source: http://www.suite101.com/lesson.cfm/17779/1067/4
> 
> ...


 :wink:  :wink:


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## susucosp (Oct 10, 2011)

i finally figure out how to use this lye calculator. 

i have a few questions:
there is no oil as carrot oil and i cannot add and i have to change my formula by take off this carrot oil and change it to olive oil and castor oil.

the formula i choose is 0 in cleansing so does it mean that there are no cleansing ability in this soap?  is soap suppose to clean?  how can it has no value in cleansing?  also, what does a high iodine value mean in the soap bar?

thanks 





> *Using a lye calculator*
> 
> Source: http://www.suite101.com/lesson.cfm/17779/1067/4
> 
> ...


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## judymoody (Oct 10, 2011)

susucosp, why do you want to try a recipe that is so complicated?  At your level of inexperience, you will have no idea of what these specialty oils will bring to the table.

How about something simple like:

60% olive oil
20% coconut
20% palm

5% superfat (don't go lower than this; it is insurance against small measuring errors and the fact that the SAP value of oils can vary from the average)

38% water (full water)

Soapcalc defaults to 5% superfat and 38% water.


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## carebear (Oct 10, 2011)

ignore the "0 cleansing" - soap is cleansing

I'd not soap with carrot or rose hip oils - their skin caring qualities will not carry through the soaping.

How about something simple like olive and coconut with a touch of castor?


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## susucosp (Oct 11, 2011)

thank you. 

i have never made soap before.  i only have very particular skin that i want to try the soap i make to fulfill my need.  if my need are fulfill, then i may consider selling soap. since i have invested a lot of time in studying how to make soap already. 2 weeks of reading and question, trial and error 2 batch of soap.

2 more questions, where do you get the value of each component fatty acid?  so, the rest of the chemical composition is not react with lye.[/quote]there is no need to do the calculations yourself.  use an online lye calculator like soapcalc.net to do the math for you.  if you prefer to do the math yourself, you can google the SAP (saponification) values.

by the way, 2 weeks is not really a lot of time invested in studying soapmaking.  nor are 2 batches.  being proficient in soapmaking takes a lot more than that!  Most of us consider a year of research and development and practice the minimum to be able to consistently produce a top quality soap.  And of course the other parts of the business are even more complex.

 I suggest you visit the millersoaps.com web site and do a lot of reading.  then to soapcalc.net to learn about many of the oils that are used and what they contribute to the soap.


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## danielle22033 (May 29, 2013)

I have a soap making book, just a basic soap making book and I was wondering about your calculations for water content.  You divide you total oils by 3 and my book says to multiply the total about of lye needed (after superfatting) by 2.5?  You're calculations seem to have more water content.  Is there a right or wrong way based on these 2 methods?  What effects would more or less water do to the soap?

Thanks


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## PrairieLights (May 27, 2014)

Maybe my brain is tired... My eyes are... Help! How can I calculate recipes according to the loaf size I want to make? I know what I want to include - I do not know how to make the calculators tell me how much of oil total if I want to make, for example, a 5-lb loaf of it, or a 3-lb loaf of it. Is there a ratio of oils to pound of finished product? My math shows 11-12 ounces of oil per pound of soap.......................... Ack. It seems I want a calculator that works a little backward. Help?


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## Skatergirl46 (May 27, 2014)

PrairieLights said:


> Maybe my brain is tired... My eyes are... Help! How can I calculate recipes according to the loaf size I want to make? I know what I want to include - I do not know how to make the calculators tell me how much of oil total if I want to make, for example, a 5-lb loaf of it, or a 3-lb loaf of it. Is there a ratio of oils to pound of finished product? My math shows 11-12 ounces of oil per pound of soap.......................... Ack. It seems I want a calculator that works a little backward. Help?



The calculator that I use is Soap Calc.  http://www.soapcalc.net/calc/SoapCalcWP.asp
You can enter how much you want in the boxes and it does all of the calculations for you. You can even choose from a few different units of measurement.


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## seven (May 28, 2014)

another one (one that is very straightforward and easy to use) is from brambleberry.com. 

you can also determine how much oil you need judging from the mold you have on hand by measuring its volume then multiply by 0.40. the result will be the total oil you need in ounces.
more on this: sticky


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## shunt2011 (May 28, 2014)

I use either soapcalc.com or wholesalesuppliesplus.com calculator.


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## PrairieLights (May 29, 2014)

I saw the math formula... And just covered volumes in teaching math to my son (home educated) and hated it - bleh. 
But it still means I will have to do some of my own math to get the percentages and pounds in alignment with the formula, right? I vote for someone to make a calculator that I can enter in "I want 10% avocado oil, 30% coconut oil, and 60% olive oil to make a 5-pound loaf mold (or 5 pounds of LS paste)" and it will do it all for me that way!  Yay! 
???
You all are awesome!
L


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## bountifulsoaps (Apr 9, 2016)

Skatergirl46 said:


> The calculator that I use is Soap Calc.  http://www.soapcalc.net/calc/SoapCalcWP.asp
> You can enter how much you want in the boxes and it does all of the calculations for you. You can even choose from a few different units of measurement.



This one seems interesting.  I've used Bramble Berry but stick with MMS.  They differ alot.  On my 80 ounces of oils Bramble Berry has me up to almost 12 ounces of lye where as MMS has me at 11.38   WHY THE BIG DIFFERENCE.  I am using the same oils on each chart.  Haven't figured out the www.soapcalc.net..There I plugged in the oils but it didn't give me a lye amount?  Have to look at that one again


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## DeeAnna (Apr 9, 2016)

This is a very old thread and not a very good one at that. Please let this sleeping dog lie. 

Please see this tutorial to learn how to use Soapcalc -- http://www.soapmakingforum.com/showthread.php?t=49627

As far as why the difference in NaOH weights from calc to calc for the exact same recipe -- the main reason is that saponification values for the various fats are not constant because fats are not perfectly consistent. If one person chooses one set of sap values for their calculator and the next person chooses slightly different sap values, those slight differences can add up. 

Also, be sure to check the "lye discount" (superfat) if you compare the calcs. Many people just accept the default lye discount which is often 5%, but there is no rule that says the default has to be 5%. It might be 4% or it might be 7% -- just make sure that number is the same if doing a comparison.


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