Soy Sauce Brine Calculator
Enter your koji and soybean mix weight and the brine strength in Baumé to get the brine volume and the salt to dissolve for the moromi.
Results
- Salt to dissolve
- 0.49 kg
- Brine strength
- 20.29%
- Mix ratio
- 1 : 1.2
Stir the moromi daily for the first weeks to keep mold off the surface, then let it ferment 6-12 months before pressing.
How the moromi brine works
Moromi wants brine equal to roughly 1.2 liters per kilogram of koji and bean mix - enough liquid to cover the mash and carry the enzymes. Strength is read in Baumé and converts to salt on the line that fits brine density to the scale (salt% = 1.11 x Bé - 0.8): 19 Bé is roughly 20% salt by weight, the classic moromi strength. Dissolve the salt fully before the mix goes in so the concentration is even from day one.
The koji incubation calculator grows the koji that feeds the moromi, and the salt weight calculator converts any salt weight into tablespoon measures for the salt you have.
Frequently asked questions
What does Baumé actually measure?
Baumé is a density scale for liquids heavier than water, and salt brine density tracks salt content almost linearly: each degree Bé is about 1.1% salt by weight over the moromi range. A Baumé or salinometer hydrometer is the traditional moromi tool; a refractometer or careful weighing works too.
Why is the brine so much saltier than pickle brine?
Moromi at 19-23 Bé runs 20-25% salt, several times a sauerkraut brine. That strength is deliberate: it suppresses unwanted microbes across the long 6-12 month ferment while the koji enzymes, which tolerate salt, break the beans into amino acids - the source of soy sauce umami.
Can I use less brine for a thicker result?
Some styles run less liquid, but home batches do best near the 1 : 1.2 ratio: less brine leaves mash exposed above the liquid, which invites mold even with daily stirring. If the mash looks too dry, mix additional brine at the same strength rather than topping up with plain water.