Calculate exact lye and water ratios for cold process and liquid soap. Manage superfat levels and lye concentration for perfect artisan soap batches every time.
Our professional Lye Calculator is a comprehensive engineering tool designed for both beginner and expert soap makers who demand precision in their craft. It provides hyper-accurate measurements for Sodium Hydroxide (NaOH) for solid bars and Potassium Hydroxide (KOH) for liquid soaps, based on the specific saponification values (SAP) of over 100 different oils, fats, and butters. Whether you are crafting a single artisanal bar of cold process soap or a industrial-scale batch of liquid soap, this tool ensures your recipe is chemically balanced, safe for skin contact, and consistently high-quality by meticulously accounting for superfatting levels and precise lye-to-water concentrations.
The calculator operates on the fundamental chemistry of saponification, utilizing the specific SAP value for each selected lipid in your recipe. The SAP value represents the exact milligrams of potassium hydroxide required to fully saponify one gram of a specific fat. For solid bar soap (NaOH), our algorithm performs a conversion by dividing the KOH value by 1.403. The core mathematical formula is: Total Lye Weight = ∑(Oil Weight_n * SAP Value_n). Once the raw lye requirement is established, we apply your 'Superfat' (or Lye Discount) percentage to leave a calculated portion of oils unreacted, which enhances the moisturizing properties and provides a safety buffer against excess alkalinity. Furthermore, the water amount is dynamically calculated based on your chosen lye concentration percentage or lye-to-water ratio, allowing you to control the curing speed and pour consistency of your soap batter.
Ideal for creating everyday functional bars or high-end artisan soaps. Use a 5% superfat with a balanced blend of Coconut, Olive, and Palm oils to achieve a bar that is both cleansing and gentle on the skin.
Specifically designed for makers using Potassium Hydroxide (KOH). This scenario helps you calculate the extra water needed for liquid soap paste dilution and accounts for the typical 90% purity of commercial KOH flakes.
For sensitive skin or luxury facial bars, adjust the superfat to 10% or higher. This ensures a significant amount of free unsaponified oils remain in the bar, providing an ultra-moisturizing and creamy lather experience.
NaOH (Sodium Hydroxide) is used to make solid bar soap. KOH (Potassium Hydroxide) is used to make liquid soap and soft pastes.
A standard 'lye-to-water' ratio is 1:2. Experienced makers often use a 'Lye Concentration' of 33% (1 part lye to 2 parts water) to speed up curing time.
The most common reasons are incorrect lye measurement, mixing at too high a temperature (causing a 'soapcano'), or 'false trace' where the soap looks mixed but isn't.