Calculate the saponification value of an oil or fat
A saponification value calculator estimates how many milligrams of potassium hydroxide are required to saponify one gram of the tested fat or oil. The measurement is commonly written as mg KOH/g and comes from a blank-corrected titration after a weighed sample reacts with excess alcoholic potassium hydroxide. Enter the sample mass, titrant normality, blank titre, and sample titre to turn those laboratory observations into one clearly labelled result.
Saponification value is useful for comparing fats, oils, waxes, and quality-control samples under a stated analytical method. In general, materials rich in shorter-chain fatty acids tend to require more alkali per gram and therefore give a higher value than materials dominated by longer-chain fatty acids. That trend is not an identity test by itself, because mixtures, free acids, unsaponifiable matter, oxidation, and the selected method can also influence the measured result.
Use the blank-corrected saponification value formula
The calculation uses SV = 56.1 × N × (Vblank − Vsample) ÷ msample. Here, 56.1 is the molar mass of KOH expressed in milligrams per millimole, N is titrant normality in equivalents per litre, both titre readings use the same volume unit, and sample mass is in grams. With millilitres for both titres, the factors combine directly to produce milligrams of KOH per gram of sample.
The blank measures the alkali available when no oil or fat sample consumes it. The sample titre should therefore be lower than the blank titre in this method, and the difference represents alkali consumed by saponification. The calculator requires the blank reading to be greater than the sample reading. If that order is reversed or the readings are equal, review the burette records, blank assignment, endpoint, reagent standardization, and sample preparation instead of forcing a zero or negative result.
Follow a saponification value example
Suppose a 4.00 g oil sample is tested with 0.500 N acid. The blank titre is 25.00 mL and the sample titre is 10.00 mL. Their difference is 15.00 mL, so SV = 56.1 × 0.500 × 15.00 ÷ 4.00 = 105.19 mg KOH/g. The displayed steps preserve the subtraction before multiplication and division, making the blank correction easy to audit.
Keep the two titre readings in one unit. Converting one reading to litres while leaving the other in millilitres creates an unusable difference and a thousandfold error. Use the actual standardized normality rather than the nominal reagent label where the method requires standardization. Record sample mass with the same basis as the method, including whether the weighed material was dried, filtered, or corrected for moisture.
Check and interpret the reported mg KOH per gram
A quick reverse check is to multiply the reported SV by sample mass, then divide by 56.1 and normality. The result should reproduce the blank-minus-sample titre difference within display rounding. A larger blank correction, stronger titrant, or smaller sample mass raises the calculated value when the other quantities stay fixed. These direction checks can reveal swapped readings or an incorrectly placed decimal point.
Compare results only when the analytical procedures are comparable. Reflux time, reagent concentration, endpoint detection, sample condition, titrant standardization, and replicate agreement all affect the laboratory value. Published ranges may help screen a known material, but a value inside a range does not prove authenticity and a value outside it does not reveal the cause. Use replicate titres, controls, uncertainty, and the applicable standard method for formal decisions.
Laboratory limits, chemical safety, and privacy
This page performs the arithmetic after an experiment; it does not tell a user how to reflux a sample, prepare reagents, recognize an endpoint, or dispose of waste. Potassium hydroxide is corrosive, alcoholic solutions may be flammable, and heated glassware introduces additional hazards. Work only from an approved laboratory procedure with appropriate training, ventilation, protective equipment, compatible equipment, and waste controls.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.