Symphony Scents Lye Calculator

Use this to calculate the amount of lye needed for a soap recipe. Enter the number of ounces (or grams, pounds, or kg) of each type of oil in your recipe, then click "calculate" at the bottom to get the amount of lye you will need.

Sodium Hydroxide is the most common type. This can no longer be found in stores as Red Devil lye. You will need to find a chemical supply company in your area, or try Boyer (boyercorporation.com); they will ship anywhere, at least in the U.S.

Potassium Hydroxide is much less common, mostly used in making liquid soaps from scratch. For this you will need to contact a chemical supply company in your area.

"Superfatting" is simply adding extra oils to a recipe, i.e. more than is necessary to consume all of the lye during the soapmaking process. One reason is just as a safety margin, in case a little too much lye is added to the soap. Another reason is just to reduce the ph of the soap and make it a little more gentle (though with slightly less lather). A common superfatting percent is 5%.