Dehydrated Food Rehydration Water Calculator

How it works

Water to add = dry weight × ratio (vegetables 2.5, mushrooms 4, beans 3, fruit 1.5, meat/TVP 2, grains 2.2) · Rehydrated weight ≈ dry weight + water absorbed

Drying food removes almost all of its water, and rehydrating simply puts that water back — but different foods hold very different amounts. Mushrooms and beans are thirsty, soaking up three to four times their dry weight, while dried fruit already holds some moisture and needs the least. Use warm or hot water to speed things along, and give dense items like beans a long soak, whereas thin vegetable flakes and mushrooms plump up in half an hour. It is better to add water gradually and top up than to drown the food, so start near these ratios and adjust. For soups and stews you can skip the separate soak entirely and let the food rehydrate in the simmering liquid, adding that water to the pot.

Worked example

You have 100 g of dried mushrooms. At a 4:1 ratio they need about 100 × 4 = 400 ml of water and rehydrate to roughly 100 + 400 = 500 g after a 20–30 minute soak in warm water.

Frequently asked questions