Free Tool for Soap Makers
Lye Calculator
Calculate exact NaOH (bar soap) and KOH (liquid soap) amounts for any oil blend. Superfat, water discount, and KOH purity adjustments included.
1 Add Oils to Your Recipe
No oils added yet. Start building your recipe above.
2 Settings
3 Your Results
NaOH — Bar / Hard Soap
—
grams NaOH (100% pure)
—
g water (% of oils)
KOH — Liquid / Paste Soap
—
grams KOH (at 90% purity)
—
g water (% of oils)
Oil Breakdown
⚠️ Always verify with a second calculator before making soap. Lye is caustic — safety goggles and gloves required.
Want the full SAP chart as a PDF? Enter your email and it's yours.
Here it is: Download the SAP chart PDF →
One page, 40 oils, NaOH and KOH values.
SAP Value Reference Chart — 40 Oils
Saponification chart for soap makers. SAP values show how much lye (NaOH or KOH) is needed per gram of oil. Formula: Lye (g) = Oil weight (g) × SAP value. Water: 33–38% of the total oil weight. Oils available from Sekiya Sourcing are highlighted.
| Oil | NaOH SAP | KOH SAP |
|---|
Ships from Georgia, USA
Oils for your next batch — US stock
Both are in the SAP table above. Laurel berry oil is the Aleppo soap ingredient; black seed oil is a cold-pressed superfat oil. COA per lot on request.
Flat $9.45 US shipping · free over $55 · in-stock orders ship within 3 business days.
What is Superfat?
Superfat (lye discount) is the % of oils left unsaponified. 5% is standard for skin-care bars — it makes the soap more conditioning and provides a safety margin for lye inaccuracies. Shampoo bars: 0–2%. Face soap: 5–8%. Body soap: 5%.
NaOH vs KOH
NaOH (sodium hydroxide) makes hard bar soap. KOH (potassium hydroxide) makes soft paste or liquid soap. KOH values are ~40% higher than NaOH because of molecular weight difference. Commercial KOH is usually 90% pure — adjust accordingly.
Water Discount
Water is measured as a percentage of your total oil weight, the convention soap calculators use: 33% gives a harder bar that cures faster, 38% is easier to work with but takes longer to harden. For swirl designs, use 33%; for hot process, 33% or less. The calculator prints the lye concentration each setting produces — check it before you mix, and never try to dissolve more lye than the water can hold.