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Grain that’s too wet bursts and breeds bacteria; grain that’s too dry colonizes slowly. This calculator tells you how much dry grain to buy for a batch of jars and how much water it needs to absorb to reach your target moisture — so you can check the result by weighing, not guessing.
How it works
Dry grain already contains about 10–13% moisture. To reach a target moisture t, the hydrated weight must be dry solids ÷ (1 − t). The difference from the dry weight is the water the grain has to absorb during soaking and simmering. Most growers aim for roughly 45–55%.
Common grains compared
| Grain | Pros | Watch out for |
|---|---|---|
| Whole oats | Cheap, easy to find | Hulls hide wet kernels |
| Rye berries | Classic, holds shape | Bursts if over-simmered |
| White millet | Many inoculation points | Small kernels clump when wet |
| Brown rice | Easy to source | Turns mushy quickly |
FAQ
How do I know the grain is dry enough?
After draining, spread it out until there’s no shiny water film on the kernels. A handful pressed in a paper towel should leave only faint damp spots.
How much grain fits in a quart jar?
About 300–400 g of dry grain fills a quart jar roughly two-thirds once hydrated, leaving room to shake.
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