Soap Lye Calculator

NaOH (sodium hydroxide) → makes solid bar soap.
KOH (potassium hydroxide) → makes liquid or soft soap. If your KOH is 90% purity (common), check the 90% KOH purity box — the calculator will divide the lye amount by 0.9 to compensate.
⚠ Lye is highly caustic. Always wear gloves and eye protection. Always add lye to water — never the reverse. Keep children away from your work area.

First, choose your unit of measurement from the dropdown — Ounces, Pounds, Grams, or Kilograms. This affects how all oil weights are displayed throughout the calculator.

Then enter your Total Oil Weight. This is the combined weight of all oils in your recipe — not each oil individually. For example, if you're making a batch with Olive Oil, Coconut Oil, and Shea Butter, enter their combined total here.

Two ways to work: Tip: 1 lb of oils produces roughly 1.4 lb of finished soap. A 2 lb batch (32 oz of oils) is a good starting size for beginners.

Choose how you want to express water using the dropdown, then enter the value:
Water as % of Oils — most common for beginners. 38% is a safe starting point. Experienced soapers often use 33–36% for a firmer bar that unmolds faster.
Lye Concentration — expresses lye as a percentage of the total lye + water solution. 30–33% is a common target range.
Water : Lye Ratio — sets the ratio of water weight to lye weight. A ratio of 2.3 means 2.3× as much water as lye by weight.
All three modes calculate the same water weight — they're just different ways of expressing it. The Recipe Summary always shows the final gram/oz/lb values.

Super Fat % — the percentage of oils intentionally left unsaponified (not converted by lye). 5% is the standard for bar soap — it adds a conditioning, skin-safe free-oil cushion. Higher values (8–10%) make a more moisturising bar but reduce shelf life. 0% is fully saponified and harsher.

🌸 Fragrance section: Example: With 2 lbs of oils at 0.5 oz/lb, you'd use 1 oz of fragrance. At 1 oz/lb you'd use 2 oz.

Use the oil browser (centre column) to find oils:
• Type in the filter box to search by name.
• Click an oil to preview its SAP values and fatty acid profile in the One/All columns.
• Double-click or press + Add to Recipe to add it to the next empty slot.
• You can also use the dropdown in each recipe row to select or swap an oil directly.

Up to 14 oils can be used in one recipe.

The recipe table has two editable columns — % of Oils and Weight — that work together in real time.

Method A — Enter total first, then percentages: Method B — Enter weights directly: Tip — enter % with no total yet: If you type percentages before setting the total, the % values are remembered (shown in amber as ← set total). Enter the total when ready and all weights calculate at once.

Use the unit selector in Step 2 to switch between oz, lb, g, and kg at any time — all values convert instantly.

Recipe Summary (left panel) — shows water, lye, total oils, fragrance, and full batch weight in lb / oz / g for your recipe as currently entered.
Recipe at a Glance (centre, section 8) — a consolidated view of all settings and calculated values in one place, useful before printing or exporting.
Soap Bar Qualities (left panel) — calculated from the fatty acid profile of your oil blend: Fatty Acid Profile (left panel) — shows the weighted breakdown of fatty acids across all your oils.

Use the Additives section (left panel) to track clays, micas, botanicals, exfoliants, milk powders, sodium lactate, etc.
Click + Add Additive, enter a name, amount, and unit. These are for reference only — additives are not included in lye or water calculations. Common usage rates:

Click the 📐 Workshop tab in the navigation bar to access tools that work with your current recipe.

📐 Batch Scaler
Enter your desired bar size (oz) and number of bars. The scaler calculates a scaled batch and shows ingredient weights (lb / oz / g) including a per-oil breakdown. A Waste % allowance (default 5%) accounts for batter left in the bowl and mold trim. You can also type a Target batch (oz) and the bar count back-calculates automatically. Press ↗ Apply to Recipe to write the scaled values back into the calculator.
The scaler shows a preview only — nothing changes until you click Apply.

💰 Cost Calculator
Enter a $/lb price for each ingredient including any additives you've added. The calculator shows total batch cost, cost per bar, and a suggested retail price (3× markup). Set your bar count in the Batch Scaler first so the per-bar figure is correct.
The 3× guideline does not include labour, packaging, or overhead — adjust your pricing accordingly.

🌸 Fragrance Blend Calculator
Add up to 6 fragrance oils with their amounts. Select a product type and the calculator checks combined IFRA compliance for the whole blend. Fragrance names auto-match your Fragrance Library — when a match is found, the IFRA limit fills in automatically. Use ← Sync fragrance oz from recipe to pull your current recipe's fragrance amount and product weight.

🗓️ Cure Date Tracker
Enter a batch name, date, and soap method. The tracker shows a progress bar, days remaining, and exact ready-to-sell dates. Batches are saved to your browser and exported with your JSON file.

The 🌸 Fragrance Library tab is your personal database of fragrance oils with IFRA compliance limits. It comes pre-loaded with 83 common fragrance names and typical industry limits.

How entries are labelled: Adding a fragrance: Click + Add Fragrance, enter the name, supplier, and the limits from your supplier's IFRA Certificate of Conformity (available on each product page at Voyageur). Enter values for Bar Soap (Category 9), Lotion (Category 5A), and Candle (Category 12).

Auto-fill in Blend Calculator: When you type a fragrance name in the Workshop's Fragrance Blend Calculator, if the name matches your library, the IFRA limit fills in automatically. A green dot ● confirms the match.

The Recipe Notes field (below the calculator) is a free-text area for anything you want to remember — technique observations, cure time, colour results, fragrance behaviour (acceleration, ricing, morphing), modifications to try next time, etc.
Notes are included in Export JSON, View Recipe Summary, Save .txt, and Print.

Use the toolbar buttons at the top of the page: 📤 Export JSON — saves your full recipe as a .json file to your computer. The file includes all settings, oil weights, additives, notes, and a calculated summary. File name is auto-generated from your recipe name.
📂 Load JSON — opens the load dialog with two options:
Both methods fully restore all settings, oils, additives, and notes. Old-format files (exported from earlier versions) are also supported.

📋 View Recipe Summary — opens a formatted modal showing your complete recipe in a clean, readable layout. From here you can Save .txt (plain text file), Export JSON, or Print.
🖨 Print — prints your recipe directly. The Oil Library table and navigation are hidden automatically so only the recipe content is printed.

Always add lye to water — never water to lye. Adding water to lye causes a violent, dangerous exothermic reaction.
Wear PPE — safety glasses and chemical-resistant gloves at minimum. An apron is strongly recommended.
Work in a ventilated area — lye dissolving in water releases fumes. Mix outside or near an open window.
Use dedicated equipment — do not use soap-making equipment for food preparation afterward.
Keep a bottle of white vinegar nearby — it neutralises lye spills on skin or surfaces.
Never leave lye solution unattended around children or pets.
This calculator is a tool, not a guarantee — always double-check your lye amount before mixing, especially for new formulas.

Scale your recipe to any batch size. Set bar size and count — everything updates automatically.

↗ Apply to Recipe

Enter your cost per pound ($/lb) for each ingredient to see total batch cost and price per bar.

Ingredient	$/lb	oz	Cost
Total Batch		—	$0.00