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Calcimator

Soap Superfat Calculator

Calculate the actual superfat percentage and excess oil in your soap batch based on oil weight, lye amount, and SAP value.

Inputs

oz
oz
%

Results

Excess Oil (Superfat)

1.63 oz

Actual Superfat

5.09%

Oil Saponified by Lye30.37 oz
Ideal Lye for Target SF4.1 oz
Lye Adjustment Needed0 oz
How to Use This Calculator
  1. Enter total oil weight and the actual lye (NaOH) amount used.
  2. Set the SAP value for your oil blend and your target superfat percentage.
  3. Review Excess Oil (superfat), Actual Superfat (%), and Saponified Oil.
  4. Higher superfat (8–10%) produces a more moisturizing but softer bar with shorter shelf life.

How the result changes with Total Oil Weight

Total Oil WeightExcess Oil (Superfat)Actual Superfat
5120.63 oz40.45%
176145.63 oz82.74%
325294.63 oz90.66%
450419.63 oz93.25%

What each input means

Total Oil Weight
Total weight of all oils/fats in the batch in ounces.
Lye (NaOH) Used
Amount of sodium hydroxide (NaOH) used in ounces.
SAP Value (NaOH)
Weighted average saponification value for your oil blend. Olive = 0.134, coconut = 0.178, palm = 0.141.
Target Superfat
Your desired superfat percentage. 5% is standard for most soap recipes.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Total Oil Weight = 32, Lye (NaOH) Used = 4.1, SAP Value (NaOH) = 0.135, Target Superfat = 5 = 4 input(s) provided
  2. Calculate Excess Oil
    Excess Oil
    1.63 = 1.63
  3. Calculate Actual Superfat
    Actual Superfat
    5.09 = 5.09
  4. Calculate Oil Saponified by Lye
    Oil Saponified by Lye
    30.37 = 30.37
  5. Calculate Ideal Lye for Target SF
    Ideal Lye for Target SF
    4.1 = 4.1

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