Lauric acid: SAP value and fatty acids
Lauric acid has a saponification value of 280 mg KOH/g. One gram needs 0.200 g of sodium hydroxide (NaOH) for bar soap or 0.280 g of potassium hydroxide (KOH) for liquid soap to turn fully into soap, before any superfat.
Key numbers
- SAP, NaOH
- 0.199607 g per g oil
- SAP, KOH
- 0.28 g per g oil
- Saponification value
- 280 mg KOH/g
- Iodine value
- 0.1
- INS
- 280
- INCI name
- Lauric Acid
Example: 100 g of Lauric acid with no superfat needs 20.0 g of 100% NaOH, or 28.0 g of 100% KOH. A 5% superfat uses 5% less.
In soap
Its main fatty acids in our cited profile are lauric (99%). The eight fatty acids used in soap-quality scores make up 99% of the profile.
On its own it scores 99 for hardness, 99 for cleansing and 0 for conditioning, with a saturated : unsaturated split of 99 : 0.
A free fatty acid, not a fat. It neutralises lye directly; no glycerin is made. Pure lauric acid needs 280 mg KOH/g; commercial grades (JSQI spec 275–285) are close to that.
Fatty-acid profile
| Fatty acid | % of fatty acids | Counts toward |
|---|---|---|
| lauric | 99% | hardness, cleansing, bubbly lather |
| myristic | 0% | hardness, cleansing, bubbly lather |
| palmitic | 0% | hardness, creamy lather |
| stearic | 0% | hardness, creamy lather |
| ricinoleic | 0% | conditioning, bubbly and creamy lather |
| oleic | 0% | conditioning |
| linoleic | 0% | conditioning |
| linolenic | 0% | conditioning |
Basis: Supplier specification for Lauric Acid 99% (C12 99% min); lauric set to the 99% minimum and the remaining 1% put in "other".
Soap-quality scores (this oil alone)
| Hardness | 99 |
|---|---|
| Cleansing | 99 |
| Conditioning | 0 |
| Bubbly lather | 99 |
| Creamy lather | 0 |
| Iodine | 0 |
| INS | 280 |
Each score adds up certain fatty acids, the way Soap Ledger scores a whole recipe. They are for comparing recipes; they don't predict how a bar will feel, and they say nothing about safety or skin.
Sources
SAP value: 280 mg KOH/g (JSQI 2021 acid-value range midpoint (pure free acid: SAP = acid value)), from Theoretical SAP of pure lauric acid from molar mass, computed (56106 / molar mass). Printed value: 56106 / 200.32 (C12H24O2) = 280.1 mg KOH/g.
Published values we checked:
- acid value 275～285 mg KOH/g — Ministry of Health, Labour and Welfare (Japan)
- 56106 / 200.32 (C12H24O2) = 280.1 mg KOH/g — computed (56106 / molar mass)
Fatty acids and iodine: Lauric Acid 99% FGK Flakes – Product Data Sheet (Dec 2011), Acme-Hardesty Co. (supplier). Also checked: Ministry of Health, Labour and Welfare (Japan) (Monograph ラウリン酸 Lauric Acid: "consists mainly of lauric acid"; acid value 275–285, mp 32–45 °C).
NaOH and KOH values are converted from mg KOH/g with the molar masses 39.997 and 56.106 and rounded to 6 decimals, exactly as in the Soap Ledger app. Real oils vary by origin, grade and lot: check your supplier's certificate of analysis. Verify every weight before you make this, and follow lye safety. Not a safety or compliance certification.
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