Sizu Home › Calculators › Cost per Unit
Opens on the book's Market Batch loaf. Switch to the candle run or the guest soaps, or type your own packs and prices.
Ingredients: pack price, pack size, and the grams this batch uses
Per unit: the pieces each bar or candle takes
Your time
Enter the ingredients and press Calculate.
The formula
- Price per kg = pack price ÷ pack size in kg (1 lb = 0.4536 kg, 1 oz = 28.35 g)
- Cost of an ingredient = grams used ÷ 1000 × price per kg
- Per unit = the batch's ingredients ÷ units + each piece (box, jar, wick, label)
- Your time per unit = minutes ÷ 60 × your rate ÷ units. Cost to make = materials + time
The book's worked example, Chapter 11. The loaf's organic oils cost 7.82, the lye 1.46 and the lavender 5.32: 14.60 a loaf, 1.46 a bar. With a 0.32 box and a 0.10 label, 1.88 a bar in materials; 90 minutes at 20 an hour adds 3.00, so 4.88 to make. A candle: 3.86 in materials, 8.02 with time.
The candle preset buys wax and fragrance with the run's 5 % spare. The hourly rate is yours to choose; the book's example is 20. Kit (molds, scale, blender) belongs in fixed costs: see the break-even calculator. Prices are illustrative US supplier prices from October 2026, shown without a currency sign; put in your own. Everything stays in your browser: no sign-up, nothing stored.