Free tool
Free during betaSoap Calculator (Lye / SAP)
Enter your oils, lye type, superfat, and water ratio. Get NaOH or KOH amounts plus live hardness, cleansing, conditioning, bubbly, and creamy scores. Built for Canadian indie soap makers and tied into FormulaNorth's ingredient and label tooling.
Soap calculators are starting points, not safety reviews
FormulaNorth helps organize cosmetic formulation, label, costing, and CNF preparation information. It is not legal or regulatory advice and does not replace Health Canada guidance, professional regulatory review, or the maker's responsibility to verify product compliance before sale.
📚 Free recipe library
15 trustworthy recipes — Castile, salt bar, milk soap, liquid, shave bar — open in calculator with one click.
🧰 Starter kit guide
Equipment, safety gear, ingredients, and Canadian suppliers for your first batch.
🪜 CP step-by-step
Full first-batch walkthrough — from weighing to cure.
Frequently asked questions
Is the soap calculator free?
Yes. No account needed. Save your recipes inside FormulaNorth by creating a free account if you want version history and label drafting.
What does superfat mean?
Superfat is the percentage of oils intentionally left unsaponified — the calculator reduces lye by that percentage so some oils stay free for moisturizing. 5–8% is typical for bar soap.
Is the SAP data accurate?
Values are industry-standard estimates from publicly available indie soap-making references. Always cross-reference with your supplier's spec sheet and zap-test or pH-test the finished bar before selling. SAP varies slightly between batches and producers.
Should I use NaOH or KOH?
NaOH (sodium hydroxide) makes hard bar soap. KOH (potassium hydroxide) makes liquid or cream soap. Pick the lye type matching the product you're aiming for — the calculator switches the SAP values automatically.
What's a safe water-to-oil ratio?
33–38% of oil weight is the standard range. Lower ratios (a 'water discount') trace faster and produce a harder bar but are less forgiving for beginners. 33% is a good default.
Is the soap I make ready to sell in Canada?
Soap with no therapeutic claims is treated as a cosmetic in Canada. Before selling, you'll need a Cosmetic Notification Form (CNF) on file with Health Canada, a bilingual label, and ingredient review against the Cosmetic Ingredient Hotlist. FormulaNorth covers all of that.
What are INS and Iodine values?
INS combines hardness and iodine to estimate overall soap quality (target ≈ 136–170). Iodine value indicates how unsaturated the oils are; lower is more shelf-stable (≤ 70 ideal for hard bars). Both are estimates — your final bar's longevity depends on cure, storage, and antioxidants.