Lacto-Fermentation Salt Calculator

Salt is what makes lacto-fermentation safe. It suppresses pathogens and mold while lactobacillus — the bacteria that acidifies the ferment — survives and thrives. As the pH drops, even salt-tolerant organisms get out-competed.

Salt weight = vegetable weight × salt percentage / 100

The right percentage depends on what you are making:

2%: classic sauerkraut, most mild European-style ferments. Enough to draw water from the cabbage and prevent surface mold without making the finished product unpleasantly salty.

2.5%: kimchi and Korean-style ferments. Traditionally the cabbage is soaked in a strong brine, around 10% salt in water, and then rinsed two or three times. That 10% is the strength of the soaking water, not the amount of salt in the recipe. What stays in the cabbage afterwards is roughly 2%, which is why 2.5% with no rinse gets you to nearly the same place with less washing up.

3%: whole brined vegetables such as pickles, peppers, green beans, carrots. Here the vegetables ferment in brine rather than their own expressed liquid, so the salt applies to the water weight. Fill in the water field for that case; leave it blank and the percentage is taken against the vegetables, which is what dry salting means.

One thing that trips people up on brined ferments: a 3% brine does not make a 3% pickle. The salt migrates into the vegetables until the whole jar sits at one concentration, and since the cucumbers were unsalted to begin with, that final figure is well under 3%. Whether you care depends on what you are making. Most recipes are written for brine weight and taste right that way. If you want the finished pickle itself at 3%, weigh the salt against the vegetables and water together, and the calculator shows both numbers.

5%: olives, longer-term room-temperature ferments. Higher salt slows fermentation significantly and extends shelf life without refrigeration.

Always use non-iodized salt. Iodine is added to table salt specifically to kill microorganisms — it kills lactobacillus right along with everything else. Use kosher salt, sea salt, or pickling salt.

Weigh your salt rather than measuring by volume. Granule size varies enormously: 1 teaspoon of table salt weighs about 6 g, while 1 teaspoon of Diamond Crystal kosher salt weighs about 3 g. Weighing eliminates the guesswork.

Temperature affects fermentation speed. At 65–75°F, 2% sauerkraut takes 4–6 weeks. At 80°F it can finish in under 2 weeks but may develop sharp off-flavors. Ferment cooler and slower for a more complex result.