Saponification value (SAP)
The amount of KOH needed to fully saponify 1 g of oil (mg KOH/g). The NaOH requirement is obtained by multiplying by the molar mass ratio (39.997 / 56.106 ≈ 0.7129).
Soap Calculator
Enter your oils and their ratios; the caustic soda (NaOH), caustic potash (KOH) and water needed are calculated instantly with superfat and purity. Results update as you change the ratios.
1Soap type
2Oils and ratios
If the SAP field is left empty, the midpoint of the range in the table is used. Enter the saponification value from your oil's certificate of analysis (COA) for a more precise result.
3Settings
Breakdown by oil
| Oil | % | g | SAP | NaOH g | KOH g |
|---|
Safety
- Sodium and potassium hydroxide are corrosive; wear safety goggles, gloves and long sleeves.
- Always add lye slowly to water, never water to lye. Dissolving releases heat.
- Work in a well-ventilated area, away from children and pets.
- Results are for guidance only. Soaps placed on the market are subject to cosmetics regulations; validate your recipe with a test batch.
How is it calculated?
Superfat
The calculated lye is reduced by a set percentage so that part of the oil stays unsaponified — a safety margin that also affects skin feel.
NaOH or KOH?
Sodium hydroxide (NaOH) gives hard bar soap; potassium hydroxide (KOH) gives liquid and soft soap. Both together are used for cream soaps.
Purity
Caustic soda and potash are not 100% pure. The pure amount is divided by the purity to get the weight to use. Rely on the label or COA value.
NaOH (g) = Σ [oil (g) × SAP / 1000] × 0.7129 × (1 − superfat) / purity
KOH (g) = Σ [oil (g) × SAP / 1000] × (1 − superfat) / purity
Water (g) = lye × (100 / concentration − 1)
Saponification value table
Values are in mg KOH / g oil. For oils covered by Codex standards the standard range is given; for others a typical literature range or the SoapCalc oil table value. Actual values vary by origin and batch.
| Oil | SAP range (mg KOH/g) | Used in calculation | NaOH (g/g) | Source |
|---|---|---|---|---|
| Apricot kernel oil | 185–199 | 192.0 | 0.1369 | Typical literature range |
| Argan oil | 189–199 | 194.0 | 0.1383 | Typical literature range |
| Avocado oil | 177–198 | 187.5 | 0.1337 | Typical literature range |
| Babassu oil | 245–256 | 250.5 | 0.1786 | Codex CXS 210-1999 |
| Baobab oil | 200 | 200.0 | 0.1426 | SoapCalc oil table |
| Beeswax | 94 | 94.0 | 0.0670 | SoapCalc oil table |
| Black cumin (nigella) seed oil | 195 | 195.0 | 0.1390 | SoapCalc oil table |
| Borage oil | 190 | 190.0 | 0.1354 | SoapCalc oil table |
| Camelina seed oil | 188 | 188.0 | 0.1340 | SoapCalc oil table |
| Camellia (tsubaki) oil | 188–196 | 192.0 | 0.1369 | Typical literature range |
| Canola oil (low erucic) | 182–193 | 187.5 | 0.1337 | Codex CXS 210-1999 |
| Castor oil | 176–187 | 181.5 | 0.1294 | Typical literature range |
| Cocoa butter | 188–198 | 193.0 | 0.1376 | Codex CXS 86-1981 |
| Coconut oil | 248–265 | 256.5 | 0.1829 | Codex CXS 210-1999 |
| Corn (maize) oil | 187–195 | 191.0 | 0.1362 | Codex CXS 210-1999 |
| Cottonseed oil | 189–198 | 193.5 | 0.1379 | Codex CXS 210-1999 |
| Evening primrose oil | 190 | 190.0 | 0.1354 | SoapCalc oil table |
| Ghee / milk fat | 227 | 227.0 | 0.1618 | SoapCalc oil table |
| Grapeseed oil | 188–194 | 191.0 | 0.1362 | Codex CXS 210-1999 |
| Hazelnut oil | 188–197 | 192.5 | 0.1372 | Typical literature range |
| Hemp seed oil | 190–195 | 192.5 | 0.1372 | Typical literature range |
| Jojoba oil (liquid wax) | 88–98 | 93.0 | 0.0663 | Typical literature range |
| Kokum butter | 190 | 190.0 | 0.1354 | SoapCalc oil table |
| Kukui nut oil | 189 | 189.0 | 0.1347 | SoapCalc oil table |
| Lanolin | 106 | 106.0 | 0.0756 | SoapCalc oil table |
| Lard | 192–203 | 197.5 | 0.1408 | Codex CXS 211-1999 |
| Laurel fruit oil | 198 | 198.0 | 0.1412 | SoapCalc oil table |
| Lauric acid | 280 | 280.0 | 0.1996 | SoapCalc oil table |
| Linseed (flax) oil | 190 | 190.0 | 0.1354 | SoapCalc oil table |
| MCT / fractionated coconut oil | 325 | 325.0 | 0.2317 | SoapCalc oil table |
| Macadamia oil | 190–200 | 195.0 | 0.1390 | Typical literature range |
| Mango seed butter | 191 | 191.0 | 0.1362 | SoapCalc oil table |
| Marula oil | 192 | 192.0 | 0.1369 | SoapCalc oil table |
| Meadowfoam oil | 169 | 169.0 | 0.1205 | SoapCalc oil table |
| Moringa oil | 192 | 192.0 | 0.1369 | SoapCalc oil table |
| Murumuru butter | 275 | 275.0 | 0.1960 | SoapCalc oil table |
| Mustard seed oil | 168–184 | 176.0 | 0.1255 | Codex CXS 210-1999 |
| Myristic acid | 247 | 247.0 | 0.1761 | SoapCalc oil table |
| Neem seed oil | 193 | 193.0 | 0.1376 | SoapCalc oil table |
| Oleic acid | 202 | 202.0 | 0.1440 | SoapCalc oil table |
| Olive oil | 184–196 | 190.0 | 0.1354 | Codex CXS 33-1981 |
| Olive pomace oil | 188 | 188.0 | 0.1340 | SoapCalc oil table |
| Palm kernel oil | 230–254 | 242.0 | 0.1725 | Codex CXS 210-1999 |
| Palm oil | 190–209 | 199.5 | 0.1422 | Codex CXS 210-1999 |
| Palm olein | 194–202 | 198.0 | 0.1412 | Codex CXS 210-1999 |
| Palm stearin | 193–205 | 199.0 | 0.1419 | Codex CXS 210-1999 |
| Palmitic acid | 215 | 215.0 | 0.1533 | SoapCalc oil table |
| Peach kernel oil | 191 | 191.0 | 0.1362 | SoapCalc oil table |
| Peanut oil | 187–196 | 191.5 | 0.1365 | Codex CXS 210-1999 |
| Pistachio oil | 186 | 186.0 | 0.1326 | SoapCalc oil table |
| Pomegranate seed oil | 190 | 190.0 | 0.1354 | SoapCalc oil table |
| Poppy seed oil | 194 | 194.0 | 0.1383 | SoapCalc oil table |
| Pumpkin seed oil | 195 | 195.0 | 0.1390 | SoapCalc oil table |
| Rapeseed oil | 168–181 | 174.5 | 0.1244 | Codex CXS 210-1999 |
| Rice bran oil | 180–199 | 189.5 | 0.1351 | Codex CXS 210-1999 |
| Rosehip oil | 187 | 187.0 | 0.1333 | SoapCalc oil table |
| Safflower oil | 186–198 | 192.0 | 0.1369 | Codex CXS 210-1999 |
| Safflower oil (high oleic) | 186–194 | 190.0 | 0.1354 | Codex CXS 210-1999 |
| Sea buckthorn seed oil | 195 | 195.0 | 0.1390 | SoapCalc oil table |
| Sesame oil | 186–195 | 190.5 | 0.1358 | Codex CXS 210-1999 |
| Shea butter | 170–190 | 180.0 | 0.1283 | Typical literature range |
| Soybean oil | 189–195 | 192.0 | 0.1369 | Codex CXS 210-1999 |
| Stearic acid (commercial) | 196–212 | 204.0 | 0.1454 | Typical literature range |
| Sunflower oil | 188–194 | 191.0 | 0.1362 | Codex CXS 210-1999 |
| Sunflower oil (high oleic) | 182–194 | 188.0 | 0.1340 | Codex CXS 210-1999 |
| Sunflower oil (mid oleic) | 190–191 | 190.5 | 0.1358 | Codex CXS 210-1999 |
| Sweet almond oil | 185–195 | 190.0 | 0.1354 | Typical literature range |
| Tallow | 190–202 | 196.0 | 0.1397 | Codex CXS 211-1999 |
| Tamanu oil | 208 | 208.0 | 0.1483 | SoapCalc oil table |
| Walnut oil | 189 | 189.0 | 0.1347 | SoapCalc oil table |
| Wheat germ oil | 183 | 183.0 | 0.1305 | SoapCalc oil table |
Frequently asked questions
How do you calculate lye for soap?
Multiply the grams of each oil by its saponification value (mg KOH/g), divide by 1000 and add them up — this is the KOH required. For NaOH multiply by 0.7129. Then reduce by the superfat percentage and divide by the lye purity.
What superfat should I use?
Bar soaps commonly use 3–8%. Liquid soaps are usually made with a lower superfat, since unsaponified oil can cause cloudiness.
Why is KOH used for liquid soap?
Potassium soaps dissolve more readily in water and stay soft, so KOH is used for liquid and paste soaps. Sodium soaps form hard bars.
Why does the result change when I change the oil ratios?
Each oil has a different saponification value. Coconut oil (248–265), for example, is higher than olive oil (184–196), so increasing it raises the lye required.
Are the results exact?
Results use the midpoint of each saponification range. For a more precise result, enter the saponification value from your oil's certificate of analysis in the SAP field.