Dual Lye Calculator — Split NaOH & KOH for Hybrid Batches

A dual lye calculator answers a narrow question: if I already know how many grams of NaOH my oil list needs at the chosen superfat, how do I express part of that duty as KOH instead? Sodium and potassium hydroxide are not one-to-one by mass—each gram of NaOH has a different hydroxide molar budget than each gram of KOH. SoapLab uses the widely cited 1.4028 multiplier to convert the “leftover” alkali share from NaOH-equivalent mass into an approximate KOH mass to weigh. That keeps the workflow aligned with how many makers already think: they run the soap calculator first, then explore splits.

Some liquid or soft soap paths lean on potassium salts, while bar formulas default to sodium. Occasionally a maker blends both to chase a particular texture, transparency story, or teaching demo. Dual-alkali planning is not required for a standard cold-process loaf—your baseline remains a single alkali and a disciplined lye calculator printout. When you experiment, document temperatures, order of addition, and whether you are making paste versus dilutable soap, because those workflows exceed what a browser form can validate.

Let L be the NaOH mass you would use if the batch were all sodium hydroxide. Let p be the percent of alkalinity you want from NaOH. Then NaOH_g = L × (p ÷ 100) and KOH_g = L × (1 − p ÷ 100) × 1.4028. The factor converts the remaining NaOH-equivalent demand into a potassium hydroxide mass on the scale. If your reference table uses a different conversion, replace the factor and keep the structure.

Even split: L = 100 g, p = 50% → about 50 g NaOH and about 70.14 g KOH. Nearly all sodium: p = 95% leaves only a small KOH line—useful when you are testing a pinch of potassium for feel. Nearly all potassium: low p pushes most mass into the KOH bucket—compare with the liquid soap calculator when that is your real process.

• Using KOH SAP columns directly in a NaOH field without converting.
• Treating the split as optional safety margin—lye is still lye.
• Confusing this tool with dissolved masterbatch math—see the masterbatch lye calculator.
• Skipping batch cards when something seizes or separates.

Wear full alkali PPE for both hydroxides; store bags labeled and sealed; never mix dry powders casually. Advanced makers may adjust for purity, hydrates, or solution-based dosing—this page assumes dry mass targets paired with your own checks. When a recipe is commercial, align conversions with your chemist or insurer, not only with a web demo.

When experimenting with splits, change alkalinity share in five-point steps and log texture—small moves beat chaotic jumps. Keep a parallel all-NaOH control batch until you trust the hybrid path.