LyewiseA soap and lye calculator that shows its math.
Lyewise works out the lye and water for your soap recipe from oil data with a published source, shows every step, walks you through soap day with numbers you can read through goggles, and keeps a log of each batch while it cures. Your recipes stay on your device.
Coming soon
Every lye number shows its math and its source.
Tap Show the math and see each oil, its SAP value, the published range it comes from and the arithmetic, with your numbers put in. Change a SAP to your supplier's value and Lyewise marks it as yours.
Oil data is built from Codex Alimentarius standards, FAO JECFA specifications, USDA FoodData Central and published papers: 51 oils, each with its source and range.
- Olive 500 g × 0.1355 = 67.73 g NaOHSAP 190 mg KOH/g, published 184-196 · Codex CXS 33
- Coconut 300 g × 0.1829 = 54.86 g NaOHSAP 256.5, published 248-265 · Codex CXS 210
- Shea 200 g × 0.1265 = 25.31 g NaOHSAP 177.5, published 160-195 · Codex CXS 325R
- 147.89 g × (1 - 5% superfat) = 140.50 g
Lye causes severe burns. Wear goggles and gloves.
Built for the kitchen table and soap day.
NaOH, KOH or dual lye, with purity
Bar, liquid and cream soap. KOH defaults to 90% purity so liquid soap is not quietly under-lyed.
Water three ways
Water as % of oils, lye concentration or water to lye ratio. Whichever you choose, the other two are always shown.
Soap day, step by step
Huge numbers, big buttons for gloved fingers, the screen stays on. Enter what the scale shows and see your real superfat.
Batch log with cure countdown
Lot numbers, notes, a photo, and a reminder on the morning a batch is ready. Saved batches never change.
Fragrance checked against your certificate
Enter the Category 9 limit from your supplier's IFRA certificate. Lyewise converts your amount to % of the finished bar and tells you if it is over.
Mold resize, citric acid, printed sheets
Fit a recipe to any loaf or round mold, add the lye citric acid uses up, and print a Letter or A4 recipe sheet with the lot number.
Free calculator forever
NaOH, KOH and dual lye, purity, three water methods, superfat, fragrance in % or oz/lb or g/kg, soap qualities, Show the math, SAP editing, soap day steps, 10 saved recipes, copy as text and a candle calculator. The lye amount, units and safety warnings are never locked.
Lyewise Pro
$9.99 once
- Unlimited recipes and your own oils
- Batch log with cure reminders, photos and lot numbers
- Printed recipe sheets and mold resize
- Fragrance limits library and citric acid adjustment
- iCloud sync and backups
One-time purchase with Family Sharing. No subscription.
Questions
Do I need an account or internet?
No. Everything runs on your iPhone or iPad, even in airplane mode. There is no sign-up and no server.
Why does my lye differ a little from another calculator?
Oils vary. Lyewise uses the middle of a published SAP range for each oil and shows the range, so a 0.1-1% difference from another table is normal. Your superfat covers it. You can enter your supplier's SAP for any oil.
Where do the fragrance limits come from?
From your supplier's IFRA certificate. Lyewise does not include an IFRA table; you enter the limit for each fragrance once and it checks every recipe.
Is it safe?
Lyewise does the arithmetic and reminds you of the basics of lye safety. Handling lye safely is your responsibility: goggles, gloves, long sleeves, and always add lye to water.