The soap calculator built for tallow.
Lye, water, fragrance and bar quality for any recipe, with tallow-first starting points and plain-English warnings. Save recipes, cost every bar and ask the AI helper when something goes wrong.
Describe the soap you want and the AI writes the recipe with the calculator's oils. One AI credit.
Start from a tallow recipe:
Oils and fats
Type percentages, or type weights and the percentages follow. The GFE tallow line uses our measured fatty-acid profile.
| Oil | % | Weight | |
|---|---|---|---|
| Total |
Batch and lye
Your recipe
Bar quality
Estimates from each oil's fatty acids. The shaded band is the usual range.
MAKER PLAN
USD 19 a month, or USD 190 a year
For makers selling at markets, on Etsy or from their own shop who want their recipes, costs and prices in one place.
- Soap and lye calculator: unlimited saved recipes, recipe cost per bar, CSV export
- Cost and pricing tool: unlimited products, materials and suppliers, cost per unit, wholesale and retail prices, marketplace fees
- Production planner: pick what to make and get one shopping list per supplier, with pack counts, costs and contacts
- AI helper inside the tools: 50 questions a month on recipes, costs and pricing
- Everything in Free
Founding rate: USD 9.50 a month for as long as you stay subscribed, if you join by 31 December 2026.
Start MakerLye is caustic. Wear goggles and gloves, add lye to water (never water to lye), work with ventilation and keep children and pets away. SAP values are typical averages from published tables; use your supplier's value when you have it, and test every recipe before you sell. Recipes you enter yourself are yours. Recipes drafted by the AI or our templates are drafts for your own use and contain Grass Fed Essentials intellectual property; they may not be resold or published as formulas. Tool terms.
QUESTIONS
Soap calculator questions
How much lye do I need for tallow soap?
Beef tallow takes about 0.143 g of sodium hydroxide (NaOH) per gram of oil before superfat. At a 5% superfat, 1,000 g of tallow needs about 136 g of NaOH. Every oil has its own value, so mixed recipes need a calculator; the one above does it for you.
What superfat should I use?
5% is the usual starting point for bars. It leaves a little oil unsaponified, so the soap is gentle and weighing errors do not leave free lye. High-coconut and salt bars often use 15 to 20%.
Is 100% tallow soap good?
Yes. A 100% tallow bar is hard, mild and long-lasting, with a small, creamy lather. Many makers swap 15 to 25% of the tallow for coconut oil for bigger bubbles and add 5% castor for a richer lather.
What lye concentration should I use?
Most bar soap is made at a 28 to 38% lye solution. Stronger solutions (less water) unmould sooner and reduce soda ash; weaker solutions slow trace and give more time to work.
Can I make liquid soap with this calculator?
Yes. Choose KOH for liquid or soft soap, or dual lye for cream soap. KOH is usually sold at 90% purity; the calculator corrects for it.
Is soap a cosmetic in the US?
Soap that is mostly fats and lye and is sold only for cleaning is regulated by the Consumer Product Safety Commission. If you claim it moisturises, add skin-benefit ingredients for a claim, or use synthetic detergents, it is a cosmetic under the FDA. Check with a regulatory specialist for your labels.
What do the soap quality numbers mean?
They are estimates from each oil's fatty-acid profile. Hardness, cleansing, conditioning, bubbly and creamy lather, iodine and INS each have a usual range; the bars show where your recipe sits. They guide a recipe; your own test batch decides it.
What does Maker add?
Unlimited saved recipes, CSV export, sending a recipe to the cost and pricing tool for the cost per bar, the production planner and 50 AI helper answers a month. USD 19 a month or USD 190 a year.