Saponification Value Calculator
Enter your back-titration data (blank and sample HCl volumes, acid normality, and sample weight) to calculate the saponification value of a fat or oil. Switch between KOH and NaOH modes, see each calculation step worked out with your numbers, and compare your result to the typical ranges for 20 common oils and fats. Results update instantly as you type.
Formula
Worked example
Blank titration = 25.00 mL, Sample titration = 15.50 mL, HCl normality = 0.500 N, Sample weight = 2.000 g, Base = KOH. Difference = 25.00 - 15.50 = 9.50 mL. meq consumed = 9.50 x 0.500 = 4.750 meq. mg KOH = 4.750 x 56.1 = 266.5 mg. SV = 266.5 / 2.000 = 133.2 mg KOH/g.
What is the saponification value?
The saponification value (SV), also called the Koettstorfer number, is defined as the number of milligrams of potassium hydroxide (KOH) required to completely saponify one gram of a fat or oil. Saponification is the base-catalyzed hydrolysis of ester bonds in triglycerides to form glycerol and the potassium or sodium salts of fatty acids (soaps). Because triglycerides are the dominant structure in most fats and oils, the SV reflects the total ester content and, by extension, the average molecular weight of the fatty acids present. A higher SV means shorter average fatty acid chains (more ester bonds per gram); a lower SV means longer chains with fewer bonds per unit mass. This makes SV one of the most informative single-number quality indicators for oils and fats in food science, oleochemistry, and soap manufacture.
How the AOCS back-titration method works
The standard procedure (AOCS Official Method Cd 3-25) dissolves a weighed fat or oil sample in alcoholic KOH and refluxes it for 30-60 minutes to drive saponification to completion. The excess, unreacted KOH is then back-titrated with a standardised hydrochloric acid solution. A blank run (no fat) is carried out under identical conditions. The difference in HCl volume between the blank and the sample tells you exactly how much KOH was consumed by the fat. Multiplying that consumption (in milliequivalents) by the equivalent weight of KOH (56.1 g/mol) and dividing by the sample weight gives milligrams of KOH per gram. The same procedure adapted for NaOH uses an equivalent weight of 40.0 g/mol instead. Normality and molarity of HCl are numerically equal for HCl (it is a monoprotic acid), so the terms are interchangeable for this calculation.
Interpreting your result and detecting adulteration
Most common edible vegetable oils fall in the range 182-200 mg KOH/g, while tropical oils high in medium-chain fatty acids (coconut, palm kernel) exceed 230 mg KOH/g. Waxes such as beeswax or lanolin give much lower values (60-150 mg KOH/g) because their ester molecules are much larger. A result that falls significantly outside the accepted range for a declared oil suggests adulteration: for example, olive oil blended with high-SV oils will show a higher-than-expected reading, while the addition of mineral oil (which does not saponify at all) lowers the SV. The unsaponifiable fraction, which includes sterols, tocopherols, and hydrocarbons, does not contribute to the SV and should be determined separately if full characterization is needed. SV is nearly always used alongside the acid value, iodine value, and peroxide value to build a complete quality profile for a fat or oil.
KOH vs. NaOH: which base to report?
International standards (ISO 3657, AOCS Cd 3-25) define the saponification value on a KOH basis, making mg KOH/g the universal reporting unit. NaOH has a lower molecular weight (40.0 g/mol vs. 56.1 g/mol), so the same fat gives a proportionally lower number if reported as mg NaOH/g: multiply by 40.0/56.1 = 0.713 to convert from KOH to NaOH basis, or divide by 0.713 to go the other way. Soap makers sometimes use a NaOH-based SAP number (often expressed as a decimal fraction like 0.134 for olive oil) as the lye ratio, where the decimal equals mg NaOH per mg oil. This calculator lets you select either base so results match your specific procedure and reporting requirements.
Typical saponification values for common fats and oils (KOH basis)
| Fat or oil | SV range (mg KOH/g) | Chain character | Typical use |
|---|---|---|---|
| Coconut oil | 248-265 | C8-C14 medium-chain | Soap, food, cosmetics |
| Palm kernel oil | 230-254 | C8-C14 medium-chain | Soap, food |
| Babassu oil | 245-256 | C8-C14 medium-chain | Soap, cosmetics |
| Cocoa butter | 192-200 | C16-C18 saturated | Chocolate, cosmetics |
| Palm oil | 190-202 | C16-C18 mixed | Food, oleochemicals |
| Lard | 193-202 | C16-C18 mixed | Food, soap |
| Tallow (beef) | 190-200 | C16-C18 saturated | Soap, candles |
| Soybean oil | 189-195 | C18 polyunsaturated | Food, biodiesel |
| Sunflower oil | 188-194 | C18 polyunsaturated | Food, cosmetics |
| Olive oil | 184-196 | C18 monounsaturated | Food, cosmetics |
| Canola oil | 182-193 | C18 monounsaturated | Food, biodiesel |
| Peanut oil | 185-195 | C16-C18 mixed | Food, cosmetics |
| Castor oil | 176-187 | C18 hydroxy acid | Cosmetics, lubricants |
| Shea butter | 170-190 | C18 long-chain | Cosmetics, food |
| Beeswax | 85-102 | C24-C30 wax esters | Cosmetics, candles |
| Lanolin | 100-150 | Complex wax esters | Cosmetics, pharmaceuticals |
Ranges from AOCS official methods and established analytical references. Values are mg KOH per gram of fat/oil. Multiply by 0.713 to convert to mg NaOH/g.
Frequently asked questions
What does the saponification value tell you about an oil?
The SV measures how much alkali (KOH or NaOH) is needed to convert one gram of fat into soap and glycerol. Because each ester bond in a triglyceride consumes one equivalent of base, a higher SV means more ester bonds per gram and therefore shorter average fatty acid chains. Coconut oil (SV 248-265) is rich in short- to medium-chain acids (C8-C14), while olive oil (SV 184-196) is dominated by the longer C18 oleic acid. The SV is also used to detect adulteration: a value outside the certified range for a particular oil signals possible blending or contamination.
What is the formula for saponification value?
SV = (B - S) x N x M x 1000 / W. B is the blank HCl volume (mL), S is the sample HCl volume (mL), N is the normality of HCl (equivalents per litre), M is the molecular weight of the base (56.1 for KOH, 40.0 for NaOH), and W is the sample weight in grams. The factor 1000 converts grams to milligrams. This is the AOCS/ISO back-titration method.
Why must the sample volume be less than the blank volume?
In the back-titration procedure, a fixed volume of alkali is added to both the blank flask (no fat) and the sample flask. The fat consumes some of the alkali during reflux. The remaining, unconsumed alkali is then back-titrated with HCl. Because the sample has consumed base, less HCl is needed to neutralise it than for the blank. If the sample volume equals or exceeds the blank, it means no net base was consumed, which indicates either no saponifiable material, an incorrectly prepared solution, or a procedural error.
How do I convert from a KOH saponification value to a NaOH lye rate for soap making?
Multiply the KOH-basis SV (mg KOH/g) by 0.7133 to get mg NaOH/g. The lye rate used in soap making is typically expressed as a decimal fraction, so divide the mg NaOH/g value by 1000: for example, olive oil at 192 mg KOH/g gives 192 x 0.7133 / 1000 = 0.137 g NaOH per gram of oil. Apply a lye discount of 5-8% from this theoretical maximum to ensure no excess lye in the finished soap.
What is the unsaponifiable matter and why does it matter?
Unsaponifiable matter (USM) refers to components of a fat or oil that do not react with alkali under saponification conditions. These include sterols (such as cholesterol and phytosterols), tocopherols (vitamin E), hydrocarbons (squalene, mineral oil), wax alcohols, and fat-soluble vitamins. Because USM does not contribute to the SV, oils high in USM can appear adulterated when tested by SV alone. Avocado oil (up to 11% USM) and shea butter (up to 17% USM) have notably low SV relative to their fatty acid profile for this reason. AOCS Method Ca 6b-53 measures USM separately.
How accurate is the saponification value for identifying an oil?
The SV provides a useful screen but not a definitive identification, because many oils have overlapping ranges. Olive oil, canola oil, and sunflower oil all fall within 182-196 mg KOH/g. Confident identification requires a combination of tests: SV, acid value, iodine value (which reflects unsaturation), and fatty acid profile by gas chromatography. SV is most powerful for distinguishing the major classes (coconut-type tropical oils, common long-chain vegetable oils, waxes) and for detecting gross adulteration.
What is a good saponification value for soap making?
There is no single ideal value. Soaps from high-SV oils (coconut, palm kernel) are hard and lather well in cold water, while soaps from moderate-SV oils (olive, soybean) are milder but lather less in hard water. Most commercial bar soaps blend high-SV and moderate-SV oils to balance hardness, lather, and skin feel. The SV helps you calculate the exact amount of lye needed for a given oil weight, ensuring full saponification without excess alkali.