Grain to Water Calculator

Written byOleh Soloninupdated 25 September 2026

Grain

Porridge

You know

Grams

Result

Water by the norm, ml300
In a small panup to 330 ml
Grain, g200
Cooked porridge, g420
Salt, g4.2
Ratio1 : 1.5 by weight, loose porridge
On a Uvelka pack
into cold water, 2 parts water to 1 part grain, 13–15 minutes on low heat after boiling
The same weight of other grains
buckwheat groats ← 300 ml → 420 g white rice 420 ml → 560 g millet 360 ml → 500 g pearl barley 480 ml → 600 g barley grits 480 ml → 600 g wheat groats 360 ml → 500 g corn grits 480 ml → 600 g

Catering norms and what the pack says

How much water buckwheat, rice, millet, pearl barley and six other grains need for a loose, thick or runny porridge, what it yields and how much salt, from the Russian catering recipe standard, with the pack instructions alongside.

Loose buckwheat takes 150 ml of water per 100 g of groats and yields 210 g. Rice takes 210 ml, millet 180 ml, pearl barley 240 ml. These are the norms from the Soviet and Russian recipe collection for public catering.

The collection gives water by weight and sizes it for 30–80 litre kettles. In smaller pans it allows a little more water, and the calculator shows how much.

How to use

Pick the grain and the porridge you want: loose as a side dish, thick, or runny.
Enter how many grams of grain you have, or how much cooked porridge you need and let the calculator work out the grain.
Read off the water, yield and salt, then the pack instructions and what the same weight of other grains would take.

Water per 100 g of grain

Thickness comes down to the ratio of grain to liquid. Loose porridges are cooked in water; thick and runny ones in water, milk or a mix. The collection has no loose norm for semolina, oat groats or rolled oats.

Water per 100 g of grain and the cooked yield. Collection of recipes for public catering (Moscow, 1982), table 8. Annex 5 of Russian Federal Penitentiary Service Order No. 818 gives similar figures that do not all match: it has 370 g of water per 100 g for thick corn porridge, not 270.
Grain	Loose	Thick	Runny
Buckwheat groats	150 ml → 210 g	320 ml → 400 g	—
Rice	210 ml → 280 g	370 ml → 450 g	570 ml → 650 g
Millet	180 ml → 250 g	320 ml → 400 g	420 ml → 500 g
Pearl barley	240 ml → 300 g	370 ml → 450 g	—
Barley grits	240 ml → 300 g	370 ml → 450 g	—
Oat groats	—	320 ml → 400 g	420 ml → 500 g
Rolled oats	—	370 ml → 450 g	570 ml → 650 g
Semolina	—	370 ml → 450 g	570 ml → 650 g
Wheat groats	180 ml → 250 g	320 ml → 400 g	420 ml → 500 g
Corn grits	240 ml → 300 g	270 ml → 350 g	420 ml → 500 g

What the pack says

Packs give the ratio in parts and the time in minutes after boiling, and the numbers differ from the catering norms: pearl barley, for one, gets five parts water on the pack against 2.4 litres per kilogram in the collection. The collection is written for large kettles, and its 1973 edition allows up to 10% more water for loose porridge in smaller pans and up to 3% for thick. For pearl barley the pack itself says to top up the water if needed.

Cooking instructions on the website of the Russian grain brand Uvelka, September 2026.
Grain	Ratio	Time
Buckwheat groats	2 parts water to 1 part grain, into cold water	13–15 minutes
Long-grain rice	2 : 1, into boiling water	15–20 minutes
Parboiled rice	2 : 1, into boiling water	20–25 minutes
Pearl barley	5 : 1, into cold water	40–50 minutes
Barley grits	4 : 1, into boiling water or milk	25–30 minutes
Corn grits	3 : 1, into boiling water	20–25 minutes
Wheat groats	2 : 1, then 2 parts hot milk after 10–12 minutes	12–15 minutes more
Semolina	10 parts milk to 1 part grain	3–5 minutes

Grain for a set amount of porridge

If you know how much porridge you need, divide by the yield. A kilogram of loose buckwheat takes 1000 ÷ 2.1 ≈ 476 g of groats and 714 ml of water; a kilogram of thick rice porridge takes 1000 ÷ 4.5 ≈ 222 g of rice and 822 ml of water. Choose "How much cooked porridge you need" and the calculator does the division.

The collection salts porridge cooked in water at 10 g per kilogram of cooked weight, and milk or sweet porridge at 4–5 g.

What this calculator shows

The water by the norm, and how much a small pan may take
The cooked yield and the salt
How much grain to use for a given amount of porridge
The pack instructions: ratio and cooking time
What the same weight of other grains would need and yield

What to keep in mind

The norms are for 30–80 litre kettles. Smaller pans take more water: up to 10% more for loose porridge, up to 3% for thick.
Salt is worked out for porridge cooked in water, at 10 g per kilogram of cooked weight.
The collection's norms table has no rows for bulgur, couscous, quinoa or brown rice, so they are not in the calculator.

Where the numbers come from

Checked against the Russian collection of recipes for public catering (1982), table 8; Federal Penitentiary Service Order No. 818 of 24 September 2019, annex 5; cooking instructions of the grain brand Uvelka · verified September 2026.

FAQs

How much water does buckwheat need?

For a loose porridge the catering norm is 150 ml per 100 g of groats, yielding 210 g; for a thick one 320 ml, yielding 400 g. A Uvelka pack says two parts water to one part groats and 13–15 minutes after boiling.

How much water for rice?

Loose rice takes 210 ml per 100 g and yields 280 g; thick porridge 370 ml, runny 570 ml. The pack gives long-grain rice two parts water to one of rice and 15–20 minutes, parboiled 20–25 minutes.

How long does buckwheat take?

13–15 minutes on low heat after it comes to the boil, according to the manufacturer. The groats go into cold water, which is brought to the boil before the heat is turned down.

How much porridge does 100 g of grain make?

Loose: 210 g from buckwheat, 250 g from millet or wheat groats, 280 g from rice, 300 g from pearl barley, barley grits or corn. Thick porridge yields 350–450 g, runny 500–650 g.

How much salt goes in?

The catering norm is 10 g per kilogram of cooked porridge made with water, and 4–5 g for milk or sweet porridge. For 420 g of buckwheat that is about 4 g.

Why does the water ratio differ so much between grains?

Because the husk and the starch decide how much a grain can take up. Pearl barley is polished — the hull and part or all of the bran are removed — and still needs about three parts water to one of grain; couscous is pre-steamed semolina and takes one to one.

Worked example

Buckwheat as a side dish

Input: Buckwheat groats, loose, 200 g of grain

Output: 300 ml water, 420 g cooked

Note: In a small pan you can go up to 330 ml. The pack has its own ratio, two parts water to one of groats, and 13–15 minutes on low heat.

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