get FermentCalc

Brine Volume Calculator

Enter how many jars you are packing, their inner diameter and fill height, and the packing efficiency to get the total brine to mix and the salt it needs.

cm

Measure inside wall to inside wall across the jar opening - a 1 liter mason jar runs about 8-9 cm, wide-mouth 2 liter jars about 10-11 cm.

cm

Measure to the level you will actually fill, not the rim. Ferments need headspace for bubbling brine and a weight, so most jars stop 3-5 cm below the lid.

%

Chopped, packable shapes run high - shredded cabbage reaches 70-80% - while whole cucumbers or cherry tomatoes settle near 55-65%. The 60% default is a safe middle ground for mixed cuts.

%

Typical lacto-fermentation brines run 2-5% salt by weight. The calculator assumes brine weighs about 1 g per ml, so the salt figure is a scale number, not a spoon number.

Results

Total brine to mix
1.22L
Salt for the batch
36.6 g
Brine per jar
0.31 L

Mix about 10% extra brine: vegetables drink liquid over the first days, evaporation lowers the level, and spare brine on hand is the easiest way to keep everything submerged.

How the batch math works

Each jar is a cylinder: volume = pi x (diameter / 2) squared x height. The packing efficiency splits that volume into vegetable space and the voids between pieces, and the brine fills those voids. One jar's brine comes from the shared jar capacity kernel, then multiplies by the jar count; salt weighs brine volume x salinity.

jar brine (L) = pi x r^2 x h / 1000 x packing; total = jar brine x jars; salt (g) = total L x pct x 10

For a single jar, the jar capacity calculator shows the full volume breakdown, and the salt weight calculator turns the batch salinity into grams and spoon measures for any salt type.

Frequently asked questions

Why do I need brine if vegetables release their own liquid?

Shredded, salted cabbage makes enough brine to submerge itself, but whole or stick vegetables such as cucumbers, carrots and beans do not. Pouring a prepared brine over them keeps every piece under the surface from day one, which is what keeps mold and surface yeast off the batch.

How much extra brine should I make?

About 10% is a practical margin: vegetables absorb liquid during the first days, some brine hides in the pouring cup, and evaporation lowers the level in active ferments. Topping up from a reserved jar of brine is far easier than mixing a new small batch at the right salinity.

What packing efficiency should I use?

It depends on the cut: tightly shredded cabbage tamps down to 70-80%, uniform sticks like carrot or cucumber spears sit around 60-65%, and whole round vegetables waste the most space near 55%. Start with the 60% default, then weigh your first real pack to calibrate your own jars.