Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Crafters, Makers & DIY
Cold Process Soap Lye & Water Ratio Calculator (NaOH)
Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
Estimate NaOH and water for cold-process soap from oil weight and superfat. Planning estimates only — verify measurements independently.
Inputs
8200
0.120.2
015
23.5
Smart analysis
Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
- Interpret
Treat this as a planning estimate
Primary result: NaOH (lye) = 116.3 g. Re-run with optimistic and pessimistic inputs to understand the range—not just a single point.
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Total oil weight (oz)
The “Total oil weight (oz)” value used in this tool’s formula. Adjust it to see results update live.
Avg SAP value
The “Avg SAP value” value used in this tool’s formula. Adjust it to see results update live.
Superfat (%)
The “Superfat (%)” value used in this tool’s formula. Adjust it to see results update live.
Water:lye ratio
The “Water:lye ratio” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Estimate NaOH and water for cold-process soap from oil weight and superfat. Planning estimates only — verify measurements independently. Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio. Example: 32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
Example: 32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
When to use this Cold Process Soap Lye
Common use cases
- Estimate NaOH and water for cold-process soap from oil weight and superfat.
- Sanity-check with this case: 32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
- The relationship is: Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
Localized examples
- Crafters, Makers & DIY: the example on this page uses the same formula as the widget.
What you get
- Fields: Total oil weight (oz), Avg SAP value, Superfat (%), Water:lye ratio
- Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
- Example on the page: 32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
How to Calculate Cold Process Soap Lye Step-by-Step
- 1Enter Total oil weight (oz), Avg SAP value, Superfat (%), then the remaining fields. Use the values you have, not a catalog average, unless that is all you know.
- 2Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
- 3Worked case: 32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
- 4Order a little extra. Resin, fabric, and clay do not read a spreadsheet.
Governing formula
Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
32 oz oils, 5% superfat → ~4.3 oz NaOH and ~10 oz water (estimate).
Example: set Total oil weight (oz) = 32, Avg SAP value = 0.135, Superfat (%) = 5, then read the result.
Variable definitions
- oilOz
Total oil weight (oz)
The “Total oil weight (oz)” field. Default 32; typical range 8–200.
- avgSapValue
Avg SAP value
The “Avg SAP value” field. Default 0.135; typical range 0.12–0.2.
- superfatPct
Superfat (%)
The “Superfat (%)” field. Default 5; typical range 0–15.
- waterToLyeRatio
Water:lye ratio
The “Water:lye ratio” field. Default 2.5; typical range 2–3.5.
- Volume math (Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.) does not include your waste, test pour, or the batch that cures wrong. Add a buffer.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Lye g = oil g × SAP × (1 − superfat%); water = lye × ratio.
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Community
Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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