Salt math, without the blog

Fermentcalc is a calculator-first reference for home fermenters. If you are shredding cabbage for sauerkraut, curing cucumbers in brine, starting a pepper-mash hot sauce or measuring out miso, this site gives you the salt mass, the brine ratio and the adjusted timing for your actual kitchen temperature. No recipe carousels. No “save your ferments” sign-up flow. No upsell.

What this site covers

• Dry-salt percentage for sauerkraut, kimchi, pepper mash and similar.
• Brine percentage for submerged vegetables — pickles, peppers, garlic, cauliflower.
• Temperature-adjusted fermentation timing anchored at 68 °F.
• Batch scaling from small jars to 5 L crocks with vessel suggestions.
• Per-vegetable and per-style reference pages with food-safety citations (in build Days 2–5).

What this site does not cover

• Beer, wine, cider, or other alcoholic fermentations.
• Dairy fermentations beyond short yogurt references.
• Sourdough — see the sister site.
• User accounts, saved ferments, comments, email collection.

Sources

Every data-backed page cites a source and a last-verified date. The primary authorities used across the site are:

• NCHFP — National Center for Home Food Preservation (nchfp.uga.edu). Authoritative on home-fermentation safety.
• FDA — the pH 4.6 threshold that separates safe ferments from botulism risk is from FDA food-safety guidance.
• USDA — the Complete Guide to Home Canning (2015 revision) for brine strengths and pickle safety.
• Sandor Katz — Wild Fermentation and The Art of Fermentation (Chelsea Green Publishing).
• Noma Guide to Fermentation— René Redzepi & David Zilber, Artisan Books, 2018.
• The Joy of Pickling — Linda Ziedrich, Harvard Common Press.
• Korean Food Foundation, Cultures for Health, and Ball Canning reference materials where specifically relevant.

Who runs it

Fermentcalc is operated as part of a small network of calculator sites by Paulo de Vries, writing from the Netherlands. If you notice an error in a data page or a calculator, please get in touch — corrections are the fastest feedback loop we have.

How this site is funded

Fermentcalc is free and collects no personal data. It is funded by display ads and by a small number of Amazon links to the equipment a home fermenter actually needs — a precise scale, jars, weights, airlocks and salt. As an Amazon Associate, Fermentcalc earns from qualifying purchases at no extra cost to you. We only ever recommend gear we would use ourselves, and recommendations are never paid placements — the math and the safety verdicts are not influenced by any commercial relationship.

Food-safety note. Fermentcalc is an educational reference, not medical or food-safety advice. Always consult local food-safety guidelines, and throw out any ferment that looks, smells or tastes wrong. See the privacy policy for data-handling details.