Saponification Value Calculator
Use this saponification value calculator to estimate how many milligrams of KOH are needed to saponify one gram of fat or oil from your blank and sample titration readings.
Result
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Quick Answer: Saponification value is calculated with SV = 56.1 × (blank - sample) × molarity / weight, where the result is typically reported as mg KOH per g of sample.
Saponification Value Calculator Formula
SV = 56.1 x (B - S) x M / W
| Variable | Meaning | Unit |
|---|---|---|
| SV | Saponification value | mg KOH/g |
| B | Blank titration volume | mL |
| S | Sample titration volume | mL |
| M | HCl molarity | mol/L |
| W | Sample weight | g |
- Measure the blank and sample: Record the HCl volume used for the blank run and the HCl volume used for the actual sample.
- Find the corrected volume: Subtract the sample titration reading from the blank reading so the result reflects the amount consumed by the oil or fat.
- Apply the molarity and constant: Multiply the corrected volume by the HCl molarity and by 56.1, the molecular-weight-based factor used in the standard expression.
- Normalize by sample mass: Divide by the sample weight in grams to express the result as milligrams of KOH per gram of sample.
Worked Examples
Worked example - Omni reference case
- Blank volume: 2.0 mL
- Sample volume: 0.2 mL
- Molarity: 0.7 mol/L
- Sample weight: 20 g
Result: SV = 3.53 mg KOH/g
This is the same setup used in the Omni FAQ example and produces a low saponification value.
Soap-making style oil - Higher saponification value
- Blank volume: 20.0 mL
- Sample volume: 5.0 mL
- Molarity: 0.5 mol/L
- Sample weight: 2.0 g
Result: SV = 210.38 mg KOH/g
A higher value often points to shorter average fatty-acid chains and stronger soap-making potential.
Lab check - Moderate result
- Blank volume: 18.0 mL
- Sample volume: 9.5 mL
- Molarity: 0.5 mol/L
- Sample weight: 2.5 g
Result: SV = 95.37 mg KOH/g
The result is noticeably lower and may indicate longer-chain or less readily saponified material.
Interpretation Table
| Range | Meaning | Action |
|---|---|---|
| Below 120 mg KOH/g | Lower saponification value | Often suggests longer average fatty-acid chains or lower soap yield potential. |
| 120 to 200 mg KOH/g | Typical oil and fat range | Compare with literature values for the specific oil to judge quality or identity. |
| Above 200 mg KOH/g | Higher saponification value | Often points toward shorter or medium-chain fatty acids and stronger soap-making behavior. |
Frequently Asked Questions
Subtract the sample HCl volume from the blank, multiply by the HCl molarity and by 56.1, then divide by the sample weight in grams.
Yes. Saponification value and saponification number refer to the same idea: the amount of alkali needed to saponify one gram of fat or oil.
A higher saponification value usually means the sample contains shorter average fatty-acid chains and can produce soap more readily.
The factor 56.1 comes from the molecular-weight basis of KOH in the standard laboratory expression for saponification value.
Related Calculators
References
This calculator is for educational and laboratory planning use. Final interpretation should be based on your method, solvent system, and reference standards for the specific oil or fat.