Soap Recipe & Lye Calculator

Get the lye right every time. Add your oils and instantly see NaOH, water, and how your bar will feel — hardness, cleansing, lather. Offline. No subscription.

Make soap with confidence. Soap Recipe & Lye Calculator does the one calculation every batch depends on — the exact lye — and shows you how the finished bar will turn out, before you pour.

Add your oils and butters, and instantly see: • Precise lye (NaOH) and water for your batch, with your superfat and water settings • A live quality readout — hardness, cleansing, conditioning, bubbly & creamy lather, plus iodine and INS — so you can balance a recipe before you make it • Everything in grams, ounces, or percentages, with a library of 50 oils and butters

Go further with a one-time Pro unlock: • Liquid soap (KOH) mode with lye purity • Fragrance & essential-oil calculator • Save and name unlimited recipes, with notes • Resize any batch to your mold • Export a clean, printable recipe sheet (PDF) to save or share

Why makers like it: • Fast, beautiful, and works 100% offline — your recipes stay on your device • Trustworthy oil data, aligned to established soapmaking references (see Data & Sources) • One-time purchase. No subscription, no account, no clutter.

SAFETY: Lye is caustic. Always wear gloves and eye protection, add lye to water (never water to lye), and make a small test batch — SAP values vary by oil source. This app is a formulation aid; safe handling is your responsibility.