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Calcimator

Cold Process Soap Calculator

Calculate the lye (NaOH) and water amounts needed for cold process soap making based on oil weight, SAP value, lye concentration, and superfat percentage.

Inputs

oz
%
%

Results

Lye (NaOH) Needed

4.1 oz

Water Needed

8.32 oz

≈ 2 sticks of butter

Total Batch Weight44.42 oz
Excess Oil (Superfat)1.6 oz
~4 oz Bars11
How to Use This Calculator
  1. Enter total oil weight in ounces.
  2. Set SAP value (NaOH) for your oil blend — look this up in a lye calculator or saponification chart.
  3. Adjust lye concentration (%) and superfat percentage (5% is typical for skin-safe bars).
  4. Review Lye (NaOH) Needed, Water Needed, Total Batch Weight, and Excess Oil.

How the result changes with Total Oil Weight

Total Oil WeightLye (NaOH) NeededWater Needed
516.54 oz13.28 oz
17622.57 oz45.82 oz
32541.68 oz84.62 oz
45057.71 oz117.17 oz

What each input means

Total Oil Weight
Total weight of all oils/fats in ounces. A typical 2 lb batch uses 32 oz of oils.
SAP Value (NaOH)
Saponification value for NaOH. Olive oil = 0.134, coconut = 0.178, palm = 0.141. Use a weighted average for blends.
Lye Concentration
Lye solution concentration (lye as % of lye+water). 33% is standard. Lower = more water = slower trace.
Superfat
Percentage of oils left unsaponified for skin conditioning. 5% is standard; 3-8% is the typical range.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Total Oil Weight = 32, SAP Value (NaOH) = 0.135, Lye Concentration = 33, Superfat = 5 = 4 input(s) provided
  2. Calculate Lye (NaOH) Needed
    Lye (NaOH) Needed
    4.1 = 4.1
  3. Calculate Water Needed
    Water Needed
    8.32 = 8.32
  4. Calculate Total Batch Weight
    Total Batch Weight
    44.42 = 44.42
  5. Calculate Excess Oil
    Excess Oil
    1.6 = 1.6

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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