The most accurate free lye calculator for cold process and hot process soap. Calculate NaOH, KOH, or dual-lye with fatty acid profiles, mold volume, fragrance dosage and visual soap quality scoring. No sign-up needed.
Calculate, visualize, and validate your formulas — no sign-in required for the core tools.
Switch between lye types mid-recipe. Dual-lye mode lets you split NaOH/KOH by percentage for semi-solid and liquid bars.
Enter water as a lye-to-water ratio or as a percentage of total oil weight — whichever your recipe uses.
Instant visualization of oleic, lauric, palmitic, stearic, and linoleic with recommended range bands for a balanced bar.
Rectangular or cylindrical molds. Fill percentage, unit toggle (g / oz), and multi-mold batch sizing.
Calculates fragrance load at your chosen percentage of oil weight. Includes a colorant estimator for accurate batches.
Replace distilled water with milk, tea, aloe, or any fluid — adjusts water weight automatically.
Scale any recipe up or down by target weight. Works in grams and ounces with one click.
Load classic formulas instantly — Palm-Free Bar, 100% Coconut, Bastille, Castile, and more.
Fully responsive — works perfectly on your phone in the kitchen or studio. No app download required.
Four steps from blank recipe to batch-ready numbers.
Select NaOH for solid bar soap, KOH for liquid soap, or dual-lye for semi-solid. One click.
Search 100+ oils, enter weights in grams or ounces. Fatty acid profiles update live as you build.
Dial in superfat %, water ratio, fragrance load, and mold dimensions. Quality scores adjust in real time.
Exact lye and water weights in grams and ounces. Export to PDF or save to batch history with Pro.
Every calculation shows a full breakdown of soap quality properties — hardness, cleansing, conditioning, bubbly, creamy, longevity — each plotted against the ideal range for a balanced bar.
Try Pro free for 7 daysSee how FormulaAlchemy compares to other soap lye calculators on the features that matter most.
| Feature | FormulaAlchemy | Others |
|---|---|---|
| NaOH, KOH & dual-lye modes | ✓ | Partial |
| 100+ oil database with SAP values | ✓ | ✓ |
| Fatty acid profile visualization | ✓ | – |
| Soap quality property bars | ✓ | ✓ |
| Mold volume calculator (rect + cylinder) | ✓ | – |
| Fragrance & colorant dosage | ✓ | – |
| Water / fluid substitution | ✓ | – |
| Mobile-first responsive design | ✓ | Partial |
| Batch history & PDF export (Pro) | ✓ | – |
| AI blend recommendations (Pro) | ✓ | – |
Custom formulas, saved batch history, PDF export, and AI blend recommendations — everything you need to run a professional soap operation.
Override the default saponification value for any oil with your own lab-tested number for maximum accuracy.
AI-assisted oil blend suggestions based on your target soap quality properties and desired superfat percentage.
Export a print-ready PDF standard operating procedure for any recipe — perfect for production batches.
Save, name, and revisit every calculation you've ever run. Never lose a successful formula again.
Compare any two saved recipes side-by-side — properties, oils, and lye amounts — in one view.
Add your own oils with full SAP values and fatty acid profiles — blends, infusions, anything you source locally.
Choose a pass length. Every new account gets 7 free Pro days automatically — no card needed to start.
Click any plan to open a WhatsApp message with the order details pre-filled. Pro access is activated manually after payment confirmation. Contact us at info@formulaalchemy.com or +880 171 100 4081.