The SAP math you already double-check — NaOH, water, superfat — plus the column no free lye calculator gives you: true cost per bar, margin at your price, and what you actually keep at a booth, on Etsy, or selling direct. Your recipe stays in your browser and exports any time.
Weights by weight, never volume — in soap, the scale is the law. SAP values come from two published charts (sources in the footnote); jojoba is really a wax and mostly escapes saponification, which its low value reflects.
NaOH bar soap only for now — the liquid-soap (KOH) math is coming. Until then, run KOH recipes through your usual calculator.
Lye is caustic — gloves on, eyes covered, and always lye into water, never water into lye. And run any new recipe through a second calculator until you trust this one. Good soapers double-check everything; we would rather earn that habit than talk you out of it.
Materials priced as what goes into the pot. Water is free; your time is not, so it gets its own line.
Set your price and see the net per bar on each channel, after materials and that channel's fees.
Soap exists the day you pour it and becomes sellable weeks later. Put the pour on the calendar, not in your memory.
Your recipes export any time — that button is a promise, not a feature. We learned from Soapee, the free recipe site that shut down April 30, 2024 and took makers' saved formulations with it. Nothing you build here is trapped here.
madekeeper.com/soap-lye-calculator — SAP values and fee rates checked July 29, 2026
SAP sources: the published saponification charts at From Nature With Love (fromnaturewithlove.com/resources/sapon.asp) and Certified Lye (certified-lye.com/lye-soap.html), checked July 29, 2026. Values are ounces of pure NaOH per ounce of oil (the same ratio works in grams); where the two charts disagree we ship the lower value — the safe direction, a touch more superfat rather than less. Fee rates as of July 29, 2026: Square in-person 2.6% + 15¢ (Square's published pricing); Etsy $0.20 listing + 6.5% transaction + 3% + $0.25 US payment processing (Etsy's Fees & Payments Policy). Simplified honestly: Etsy's fees also apply to shipping you charge, and Offsite Ads (12–15% when they bring the sale) aren't included. A booth or table fee is its own cost — this page prices the bar, and the fair profit calculator prices the day.
Want the batch to price itself?
In MadeKeeper this math runs automatically on every batch — your real oil and lye costs come from inventory, each loaf computes its own cost per bar, and cure dates get watched so nothing sells early. See what MadeKeeper tracks for soap makers (there's a page for goat-milk soap too) or poke around the live demo. Free during the founding pilot, $19/mo founding rate after — locked for life.
Every lye calculator on the internet will hand you a NaOH weight. Almost none will tell you what the bar cost you — and none will tell you what you keep after Square or Etsy takes its cut. That gap is where underpricing lives. A $7 bar with $1.40 of materials looks comfortable until the fees, the labor, and the booth fee each take their bite. The math below is the same math the calculator runs; do it once by hand and you'll trust the tool more, not less.
Superfat is lye you deliberately leave out. At 5% — the convention most calculators default to — the lye saponifies 95% of your oils and the last 5% stays free in the bar as skin-loving oil. It's also your safety cushion: published SAP values are ranges, not constants, and the superfat absorbs that slack so a slightly hot lot of lye or a slightly off oil never leaves free lye in a bar. Coconut-heavy recipes often run 15–20% because coconut soap cleans hard; a castile gets by at 5%.
Water is only there to carry the lye into the oils — all of it leaves during the cure. Old-school full water is around 38% of your oil weight; a discount just means using less. This calculator defaults to 33%, a common working number: less water traces faster, unmolds sooner, and shrinks less on the rack, but it shortens your working time for swirls. If you think in lye concentration instead, flip the toggle to a water:lye ratio — 2.5:1 is about a 28.5% lye solution.
Because oils are agricultural products, not lab reagents. A saponification value is measured from real fat, and it moves with the crop, the season, and the refining — so the references publish ranges, and every calculator picks its own point inside them. That's why the same recipe wants slightly different lye on two calculators, and it's one of the jobs superfat quietly does: a 5% cushion swallows the difference between anyone's chart and your actual jug of oil. Where our two published sources disagree, we ship the lower value — more superfat, never less. It's also why the safety note above says to double-check new recipes. We mean it.
Cash on the rack. A loaf poured today is real money — oils, lye, fragrance, bought and paid for — that can't become revenue until the cure finishes, usually four to six weeks for cold process and longer for castile. The bars harden as the water leaves, which is why a cured bar weighs less than the poured weight this page shows. The practical math: count back from your market calendar, not forward from when you feel like soaping. A batch poured six weeks before the fall shows is inventory; the same batch poured two weeks before is decoration.
Nowhere. The calculator runs in your browser, the recipe is kept in local storage on your device, and the export button hands you a CSV or plain-text copy any time. No signup, nothing uploaded. We learned this one from Soapee — the free recipe site that shut down April 30, 2024 and took makers' saved formulations with it. Your recipes should live somewhere you can walk out of. (Clear your browser data and they go with it — export first.)