🍳 Cooking & Baking

Fermentation Brine & Salt Calculator

Calculate the exact grams of salt for a safe lacto-fermentation brine, or dry-salt percentage for kraut-style ferments, with presets for sauerkraut, pickles, kimchi and fermented hot sauce.

Built and maintained by Paul Clark, Redmoon Software · Checked against what this tool computes on August 26, 2026

Method

Target salt %

Salt type Only affects the tablespoon figure — grams are grams.

Water volume (mL)

Salt needed

— g

≈ — tablespoons of fine salt (varies by salt type)

Metric	Value

Quick reference

Salt percentage by weight is the safe, precise way to measure a ferment — a kitchen scale beats measuring cups because salt brands vary enormously by volume. Diamond Crystal kosher salt has large, hollow flakes and is much less dense than Morton kosher salt or fine table salt, so "two tablespoons" can mean very different amounts of actual sodium chloride depending on what's in your pantry.

The brine method dissolves salt into added water for whole or cut vegetables (pickles, olives, hot sauce peppers) that need to be submerged. The dry-salt method massages salt directly into shredded vegetables (sauerkraut, some kimchi), drawing out their own liquid to form the brine — no added water needed.

Too little salt risks unsafe spoilage from undesirable bacteria and mold; too much just slows or stalls fermentation and makes it too salty to eat. Always weigh your salt — don't eyeball it.

How it works

Both modes run the same arithmetic: salt grams = weight × target salt % ÷ 100. In Brine (submerged vegetables) mode the weight is the water volume in millilitres, treated as grams at 1 g/mL. In Dry-salt (shredded, kraut-style) mode it is the vegetable weight in grams instead. The tablespoon figure underneath divides that result by a fixed 17 g per tablespoon, and the brine row also restates your water in US cups at 236.588 mL per cup.

Target salt % decides everything, and the five presets simply write a number into that one field: 2% for Sauerkraut, 2.5% for Kimchi, 3% for Fermented hot sauce, 3.5% for Pickles and 8% for Olives. Shredded vegetables with lots of cut surface ferment safely at the low end. Whole cucumbers and chillies sit higher because brine has to penetrate intact tissue, and olives need the extreme figure to debitter over months.

One thing to watch: brine mode takes the percentage against water alone, not against water plus the vegetables you submerge in it. Once produce goes in it releases its own liquid and absorbs salt, so the finished ferment sits below the number on screen — many recipes instead calculate on total combined weight. The tablespoon conversion is also pinned at 17 g, close to fine sea salt but badly wrong for flaky kosher. Weigh the salt.

Frequently asked questions

Does a 2% brine mean 2% of the water or 2% of everything in the jar?

In Brine mode the tool takes 2% of the water volume you enter, treating 1 mL as 1 g. The vegetables are not counted. Recipes that base the percentage on combined water plus vegetable weight will ask for more salt for the same jar.

How much salt goes into a litre of water for a 3.5% pickle brine?

35 grams, or about 2.06 tablespoons at the tool's 17 g per tablespoon. That is the Pickles 3.5% preset with the water field left at 1000 mL. Halve the water and the salt halves with it, since the ratio is linear.

Why does the tablespoon figure not match my box of kosher salt?

The conversion is fixed at 17 grams per tablespoon, which suits fine sea or table salt. Diamond Crystal kosher runs closer to 10 g per tablespoon and Morton kosher about 15, so measuring by volume can leave you a third short. Use a scale.

Should I pick brine or dry-salt mode for kimchi?

Dry-salt if the cabbage is shredded and you want it to make its own liquid; brine if you are salting whole leaves or quarters in added water. The Kimchi 2.5% preset sets the same percentage either way — only the weight it multiplies changes.

Is 8% salt really necessary for olives?

The Olives 8% preset reflects the long cures raw olives need to lose their bitterness over weeks or months at room temperature. It sits far above the 2–3.5% used for vegetables, where a brine that strong would simply stall fermentation instead.

Salinity by weight, and why the default is 2%

Brine strength here is a percentage of the water weight, defaulting to 2% — the middle of the usual band for vegetable ferments. Below about 1.5% the brine is permissive enough that spoilage organisms compete successfully with the lactobacillus you want; above about 5% fermentation slows to a crawl and the result is closer to a salt cure.

Salt is doing a specific job: it selects for salt-tolerant lactic acid bacteria and against most of what would otherwise rot the vegetable. It is not a seasoning decision, which is why guessing it is a bad idea.

Which salt, and the spoon that changes everything

The salt-type selector exists because grams per tablespoon varies by about a factor of two between salts — Diamond Crystal's hollow flakes weigh roughly half what the same spoon of fine table salt does. Measuring brine salt by spoon without accounting for that can halve or double the actual salinity.

The tool defaults to 18 g per tablespoon and lets you set your own. Weighing is better than any spoon conversion.

Avoid iodised salt and anything with anti-caking agents: iodine inhibits the bacteria you are cultivating and anti-caking agents cloud the brine. Plain salt and non-chlorinated water are the two inputs worth being fussy about.

A note on cup sizes across this site

This tool converts cups at 236.588 ml — the US customary cup — while the cups-to-grams converter uses 240 ml, the figure used on US nutrition labelling. Both are legitimate definitions in active use and the difference is about 1.4%, which is immaterial for a brine and can matter in baking.

It is mentioned here because knowing which definition a tool uses is the sort of thing that should not require reading the source.