Using Lye Calculators

by Lori Young
(Port Alberni, B.C.)

I am a first time soaper and for the life of me I cannot figure out the lye calculators. It gives me different percents of lye to use???

I thought the calculators where to determine how much lye to use? Help just don't understand. What percent of lye is suppose to be used in soap....I am soo excited to start making soap, I cant stop thinking about it. I think I have totally overwhelmed

I just love all your soap, In my opinion it is the prettiest soap I have seen on line. You are my insperation, but for now I just want to make a decent first bar of
Thank You for your time, You obviously love your soap.

Lori Young,
Vancouver Island,

Hi Lori,

Lye calculators can be confusing to begin with but once you get the hang of it you'll find them quite easy. Much better than calculating the amounts by hand.

Each and every oil requires a different amount of lye in order to saponify completely and become soap. Every recipe will have a different percentage of lye concentration and that percentage depends on the amounts and types of oils used. There isn't a single percentage of lye that is used. In fact, I wouldn't even worry about lye percentages at all...I don't.

I'll use SoapCalc as an example since it's my favorite lye calculator.

Each box on the lye calculator has a number.

Box #1 lets you choose between sodium hydroxide and potassium hydroxide. Since the plan is to make bar soap, you want to pick sodium hydroxide (NaOH)

Box #2 allows you to choose the weight of the oils in your recipe. All my recipes are 900 grams since that is the amount that fits my little 6" x 6" soap mold.

Box #3 can be confusing...just click the "water as % of oils" option and put 36 in the box. That's usually how much water I use in my recipes.

Box #4 lets you decide how much free oils will be left in your soap at the end of the saponification process. I usually go with the standard 5% though some of my recipes have 8% and a very select few have more.

Box #5 gives you information about the makeup of the oils you can choose and provides a list of those oils to select and add to box #6

Box #6 is where you add or subtract the oils you want. Put in Coconut, Palm and Olive.

Box #7 is where you input the amounts of those oils. Enter 30% for Coconut, 30% for Palm and 40% for Olive.

Box #8 is where you calculate and view the recipe.
Click on Calculate and then on View recipe.

Your recipe will appear as a new page. The pink zone will show the amounts of water and lye needed in your recipe.

The water should read 342 grams and the lye should read 129.728 grams...that is how much lye you percentages necessary.

The green zone below the pink one will list the amounts of each oil needed.

It's that easy.

Keep in mind that each lye calculator will probably have slightly different results since the SAP values put into the programs will vary a bit.

Give it a on the numbers in the the SoapCalc instructions under the 'Learn' tab....generally mess around with the lye calculator for awhile.

It's a fantastic tool once you learn how to use it.

Have fun,

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Thanks So Much !
by: Lori

Thank you so much Cathy. Your feedback is greatly appreciated. I am sooo looking forward to making my first batch of soap. I am just waiting for the last of my ingredients to arrive. Again, thanks for your quick and very informative feedback.


by: Diane

Thank you for explaining this. I have been ready to beat my head against the wall. I really appreciate the way you made it seem so simple!


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