Free Lye Calculator for Cold-Process & Liquid Soap
A dual-lye NaOH + KOH saponification calculator with superfat, water discount, and instant INS scoring. Free, no signup — the same deterministic engine that powers Loovay's full formulation workstation.
Recipe
Ready to save, batch, and version your recipes?
Free plan includes the AURA AI mentor, 309-item ingredient library, and INCI / IFRA / Clean-Beauty compliance scans.
A modern, mobile-friendly UI over the same industry-standard SAP math you already trust from traditional web calculators — with cloud recipe storage, INCI, IFRA, and Clean-Beauty compliance built in.
Dual NaOH + KOH support, superfat 0-20%, water 20-45%, INS scoring, fatty-acid radar — everything a CP or HP recipe needs.
Zero AI training guarantee. All math runs deterministically — no LLM ever sees your ingredient ratios.
How to use a dual-lye calculator
Plan a soap formula with clearer starting numbers.
Start with the oils you intend to use and enter the weight of each one in grams. Loovay combines each oil's saponification value with your total batch size to estimate the sodium hydroxide and potassium hydroxide needed for the selected lye split. A 100% NaOH split is common for firm bar soap, while adding KOH can create a softer or more soluble formula. The calculator shows both values so you can document the exact starting point for your lab.
Superfat leaves a calculated portion of oils unsaponified, which can change the feel and conditioning profile of a finished bar. Water percentage affects how fluid the batter may be and how quickly it can move through trace. INS is a comparative planning signal, not a pass-or-fail grade: use it alongside the fatty-acid profile, your mold style, fragrance behavior, and the process you plan to use. Small adjustments are easier to evaluate when you change one variable at a time and keep detailed batch notes.
Every result is a theoretical estimate based on standard SAP values. Oils, lye purity, temperature, additives, and supplier variation can change how a batch behaves. Confirm all measurements with a calibrated scale, follow safe lye-handling practices, and bench-test before producing or selling a formula. When you are ready to save versions, calculate cost per unit, generate an INCI list, or track cure data, create a free Loovay studio.