Soap Mold Calculator
Measure your mold, and this tells you exactly how much oil (by weight) your recipe needs to fill it — no more overflowing molds or short batches.
Your Mold
Oils Needed
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Ounces of oils
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Grams of oils
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Est. total batch wt
About the 0.4 rule: multiplying your mold’s volume (in cubic inches) by 0.4 is the standard soapmaker’s rule of thumb for estimating the weight of oils a mold holds. Total batch weight is estimated at 1.35× the oil weight — treat it as a starting point and confirm with a lye calculator.
