Superfat is the percentage of oils left unsaponified in your soap. A 5% superfat uses about 5% less lye than the amount that would turn every drop of oil into soap, leaving ~5% as free, conditioning oil. It is also called a lye discount. Enter your base lye and a superfat below to see the adjusted amount.
Lye at 5% superfat
95 g NaOH
| Superfat | Lye (g) | Oils left unsaponified |
|---|---|---|
| 0% | 100 | 0% of oils |
| 3% | 97 | 3% of oils |
| 5% | 95 | 5% of oils |
| 8% | 92 | 8% of oils |
Don't know your base lye? Get it from your oils with the full SoapCalc calculator, then adjust the superfat here.
Calculate lye from your oils
Don't know your base lye? Pick your oils and weights below to get the lye, water and a live INCI label draft at the superfat you choose.
Oils & butters
70%NaOH lye
91.9 g
Water
186.6 g
Ingredient label (draft)
Olea Europaea Fruit Oil, Elaeis Guineensis Oil, Aqua, Sodium Hydroxide
Pre-saponification draft in descending order of weight — review it before using it on a product.
Save this label & recipe — 30 days free, card required, cancel any timeRecommended superfat by soap type
| Soap | Typical superfat | Why |
|---|---|---|
| Cold-process bar (common starting point) | 5% | Lye discount; not a release test |
| Facial / sensitive bar | 5-8% | Extra conditioning |
| High-coconut / high-cleansing bar | 7-8% | Offsets harshness |
| Salt (spa) bar | 15-20% | Salt is drying |
| Liquid soap (KOH) | 0-3% | Excess oil clouds it |
| Laundry / cleaning soap | 0-1% | Maximum cleansing |
How superfat works
Every oil needs a specific amount of lye to saponify (its SAP value). Add up the lye for 100% of your oils, then apply the superfat: lye = base_lye × (1 − superfat/100). Less lye means some oil is never converted and stays in the bar as skin-loving free oil.
Don't go too high
More superfat is not always better. Above ~8% for everyday bars, the soap gets soft, lathers less, and is more prone to DOS / rancidity as the free oils oxidize. Match the superfat to the soap, not the maximum.
Build a full recipe in SoapCalc — it computes the lye from your exact oils at any superfat, then saves and scales the recipe.
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