Utilities
Lyestone
Soap lye calculator
iOSfor iPhone and iPad
- $2.99 one-time purchase
- No account
- No ads or app telemetry
Screenshots
1 image · iPhone 6.7"
iPad
1 image · iPad Pro 12.9" (3rd gen)
If you make soap from scratch, you already know the one number you cannot guess: how much lye a given blend of fats needs to saponify cleanly. Lyestone is a lye calculator for exactly that. Choose your oils, enter the grams, set a superfat and water amount, and it works out the sodium hydroxide for bar soap or the potassium hydroxide for liquid soap. The same recipe, either lye, without redoing the math.
It ships with a library of common saponifiable fats and their SAP values for both NaOH and KOH, so you are not copying figures off a website in another tab. Alongside the lye weight it shows the qualities soap makers actually judge a recipe by, including hardness, cleansing, conditioning, and lather, each with a target band, plus iodine and INS values and plain warnings when a blend is likely to dry the skin.
For people who batch at scale there is a lye-concentration mode, fragrance and salt figures, and a one-tap share to drop a recipe into your notes. It runs the same on a phone and on an iPad propped up on the workbench.
Lyestone works entirely offline and is a single $0.99 purchase, with no account, no ads, and no subscription. Lye is caustic, and the app is a hobbyist reference rather than a substitute for gloves, goggles, and careful practice.
About Lyestone
Lyestone is a soap maker's lye calculator that lives on your phone, not behind a paywall and a slow website.
Pick the fats in your recipe and enter their grams. Set your superfat and water. Lyestone computes - in real time, as you slide - the exact grams of sodium hydroxide (NaOH) for a bar soap, or potassium hydroxide (KOH) for a liquid soap. Same recipe, both lye types, one tap to switch.
WHAT'S BUNDLED
• 43 saponifiable fats, ready out of the box - olive, coconut (76 and 92 degree), palm, palm kernel, lard, tallow, castor, shea, cocoa butter, mango butter, kokum, hemp, sweet almond, avocado, jojoba (treated correctly as a wax), babassu, sunflower, rice bran, sesame, neem, soybean, peanut, walnut, hazelnut, apricot kernel, grapeseed, evening primrose, argan, abyssinian, tamanu, meadowfoam, andiroba, rosehip, borage, pumpkin seed, marula, baobab, camelina, perilla, poppy seed, pomegranate, and beeswax.
• SAP values for both NaOH and KOH, cross-checked against canonical references (SoapCalc, ModernSoapmaking.com, the Handcrafted Soap & Cosmetic Guild table).
• Per-recipe quality scores - hardness, cleansing, conditioning, bubbly, creamy - with a visible target band so you can tell at a glance whether your recipe is balanced.
• Iodine value (DOS risk) and INS, the two most-cited stability numbers.
• Quality warnings drawn from the literature: low conditioning, high cleansing, coconut-group dominance, wax-trace acceleration, KOH-superfat advisories, and more. Lyestone will tell you why your recipe is going to dry skin - before you pour it.
PROFESSIONAL FEATURES
• Lye concentration mode (master-batchers, soap-soaping by-the-spreadsheet types) - pin lye as a percentage of total solution instead of water-as-percentage-of-oils. 33% is one tap away.
• Fragrance load in oz/lb of oils → grams. Salt addition. Milk-soap flag with a reminder to freeze the milk.
• Markdown / CSV share - drop the calculation into your woodshop notebook, Reminders, or Messages with a single tap.
• Per-fat detail cards: SAP values, contribution scores, iodine, INS, plus a one-line note on how the fat behaves in a bar.
DESIGN PROMISE
No accounts. No analytics. No internet. No ads. Lyestone is a one-time $0.99 purchase - no subscriptions, no tiers, no unlocks. The app works the same on your phone, your iPad on the workbench, and the iPad locked in the woodshop.
SAFETY
Sodium and potassium hydroxide are highly caustic. Always wear gloves and goggles. Add lye to water (not water to lye). Lyestone is a hobbyist reference - consult primary sources and a soap-making mentor before scaling production.
A Shadowfetch app. Published on the App Store by Robert Corbin.