Getting your Salt Right

Salt is key to lacto-fermentation. It keeps bad microbes out and gives the good ones room to work. Getting it right is an important skill for your fermentings. The math is fairly simple once you understand what you're doing, but it can be confusing when recipes breeze right past it.

Why Salt Percentage Matters

Eyeballing salt works fine in cooking. In fermentation, it controls what lives in your jar. Too little and the wrong bacteria move in. Too much and fermentation stalls and and your pickles get weird.

Most vegetable ferments do well in this range:

Salt %	Best for
2–3%	Most vegetables - sauerkraut, kimchi, pickles
3–5%	Longer ferments, hot weather, whole vegetables
5%+	Long-term preservation, cured meats, things that you want to taste very salty. I never do this.

When in doubt, use 2.5% by total weight. It works for almost any vegetable ferment and gives you room for error.

The Main Ways to Measure

There are a few methods out there. They all work fine, but you do want to stick with the method your recipe calls for.

Percentage of total weight (most consistent)

Salt is calculated as a percentage of everything going into the jar: vegetables, water, all of it. This works for dry-salted ferments and brine ferments alike, and it's the most repeatable method. When making a brine, just weigh your vegetables and water together and calculate from the combined total.

Brine percentage (salt as % of water only)

Some recipes calculate salt against the water weight only, not the vegetables. Common for whole-vegetable ferments where you make a brine separately and pour it over. Check your recipe before you start.

By volume (measuring spoons or cups)

No scale? You can measure by volume. Less precise, but it works if you use the right salt consistently. More on this below.

Check your recipe first. "3% brine" calculated from water weight gives you a different result than "3% of total weight." Both are valid; they're just different methods, and mixing them up will throw off your batch.

Using a Scale

A kitchen scale in grams is your best tool for fermentation. It removes all the variability that comes from different salt types and crystal sizes.

Method 1: Percentage of total weight

Weigh everything going into the jar, then calculate salt from that number. Works for both dry-salting and brine ferments.

Formula:

salt (g) = total ingredient weight (g) × target % ÷ 100

Example: sauerkraut: 1,000 g of cabbage at 2.5%; 1,000 × 0.025 = 25 g of salt

Example: pickle brine: 500 g cucumbers + 800 g water = 1,300 g total at 2.5%; 1,300 × 0.025 = 32.5 g of salt

A note on the math: This formula is technically a small approximation, similar to baker's percentages in bread baking. To hit exactly 2.5% salt by final weight, you'd account for the weight of the salt itself: salt = total weight × 0.025 / 0.975. For 1,000 g, that's 25.64 g instead of 25 g. Less than a gram. It doesn't matter for fermentation. Use the simple formula.

Method 2: Brine percentage (water weight only)

Some recipes calculate salt against water weight alone. Same idea, different base number.

Formula:

salt (g) = water weight (g) × target % ÷ 100

Example: 1,000 g of water at 3%; 1,000 × 0.03 = 30 g of salt

Measuring by Volume

It's actually totally possible to ferment foods without a kitchen scale. Measuring spoons work, but different salts have very different densities, so results will vary.

Approximate conversions per 1 cup (240 ml) of water:

Salt type	~1 tsp gives you
Fine sea salt	~1.5–2% brine
Kosher salt (Morton)	~1–1.5% brine
Kosher salt (Diamond Crystal)	~0.8–1% brine
Pickling salt (fine)	~1.5–2% brine

Diamond Crystal vs. Morton: A teaspoon of Diamond Crystal has about half the salt of a teaspoon of Morton because the crystals are larger and lighter. If your recipe calls for salt by volume, use the same brand it was written with.

If you're not sure, taste your brine. At 2–3%, it should taste pleasantly salty, like a light soup broth. Once you find a salt you like, stick with it. Consistency matters more than which salt you pick.

A few other salt tips

You'll notice the recipes call for sea salt, but don't always say why. Table salt is generally iodized, which can contribute to off-flavors. Iodine is also an anti-bacterial agent. Technically it's a low enough percentage that it doesn't slow fermentation, but most folks avoid the risk. Table salt also often contains anti-caking agents which can cloud up your brine. Sea salt is just the salt from the ocean.
Salt only protects the food that it's covering. To protect fully from mold and such, keep things submerged under the brine. Stay tuned for a future how-to on different methods for fermentation weights.

TLDR

Check what your recipe calls for, total weight, water weight, or volume.
Default to 2.5% of total weight if you're unsure. It's hard to go wrong.
Use a scale if you can. Weigh everything together for the total-weight method.
If measuring by volume, stick to one salt brand. Density varies a lot between types.
Write down what you did. When a batch turns out great, you'll want to repeat it.