Calculate a NaOH or KOH soap recipe

What you will accomplish

You will calculate a soap recipe with either sodium hydroxide or potassium hydroxide. You will enter each oil weight, choose one of three water methods, review lye and batch totals, assess Soap quality metrics, and compare the result when your tier includes comparison.

Before you start

Confirm the identity and SAP data for every oil or butter. Gather the actual lye purity from its supplier documentation and decide on a superfat target. Wear appropriate protective equipment and follow an established lye-handling procedure; a calculation does not replace safe manufacturing practice.

Enter the oil blend

1. Open the Soap Calculator. Go to /calculators/soap.
2. Select an oil. Choose the correct oil or butter from the available records.
3. Enter Weight (g). The calculator accepts each oil weight in grams.
4. Select Add Oil. Add another row for each material in the oil blend.
5. Review every row. Confirm that each weight belongs to the intended oil before calculating.

When opened from /formulas/[id]/soap-calculator, the calculator can preload compatible formula rows and the formula batch size. Review the prefilled oils before relying on them.

Set lye, superfat, and water

1. Choose Lye Type. Select NaOH for sodium hydroxide or KOH for potassium hydroxide.
2. Enter Lye Purity (%). Use the value for the lye material you will actually use.
3. Enter Superfat (%). Use the target established for this recipe and process.
4. Choose Percentage of Oils. Use this method when water is defined as a percentage of total oil weight.
5. Choose Lye Concentration. Use this method when the lye solution concentration is the controlled value.
6. Choose Water to Lye Ratio. Use this method when water is defined as a multiple of lye weight.
7. Enter the value for the selected method. Verify that its percentage or ratio basis matches your source recipe.

Choose only one water method for a calculation. There is no Dual Lye option.

Add optional inputs and calculate

1. Enter Fragrance (% of oils) when needed. Use a verified usage level for the intended product.
2. Enter Additional Additives Weight (g) when needed. Include colorants, exfoliants, or other additions that belong in the batch total.
3. Select Calculate Soap Recipe. Resolve any validation errors before reviewing the result.

Review quality and compare recipes

1. Review the primary result. Check the selected lye amount, lye concentration, total oils, water needed, total batch weight, water-to-lye ratio, and fragrance amount when used.
2. Review cure guidance. Treat the estimated range and factors as planning information, then confirm the actual product before release.
3. Review Soap quality results. Examine hardness, cleansing, conditioning, bubbly and creamy lather, iodine, INS, and the underlying fatty-acid profile.
4. Select Compare when available. Pro comparison lets you evaluate the current result beside a saved soap formula.
5. Investigate meaningful differences. Confirm that oil selection, weights, lye type, purity, superfat, and water method explain the comparison.

Do not use Save as Formula: the calculator does not create or update a formula record. If the recipe is represented by a saved formula and needs a different batch size, use the separate formula scaling workflow.

Check your work

• Every oil and oil weight matches the intended recipe.
• The selected lye is NaOH or KOH and its purity matches the supplied material.
• Exactly one water method and its correct basis were used.
• Lye, water, total oils, and total batch weight are internally consistent.
• Soap quality and cure results have been reviewed as estimates, not release evidence.
• The final recipe has an independent safety review before manufacturing.

If something does not look right

• If an oil is missing, confirm that the correct material and SAP data are available before calculating.
• If validation fails, check for empty oil selections, zero weights, or out-of-range settings.
• If the lye amount changes sharply, recheck lye type, purity, superfat, and every oil's SAP data.
• If the water amount is unexpected, confirm which of the three water methods is selected and how its value is expressed.
• If Compare is locked, confirm that your subscription includes soap-recipe comparison.

Next steps

• Review every formulation calculator
• Scale a saved formula for production
• Record the reviewed recipe and safety decision in the appropriate formula or development record.