Hong Life CalculatorsUnderstanding the rice to water ratio calculator — concept and principle
This calculator turns a weight of raw rice into the amount of cooking water, using the volume ratios cooks actually measure with, and estimates how much cooked rice you will get. It is handy when you weigh rice on a scale but your recipe or habit is "one cup of rice to so many cups of water".
How it is calculated
- Rice volume (mL) = rice (g) ÷ 0.8, because 1 mL of raw rice weighs about 0.8 g.
- Water (mL) = rice volume × ratio. Ratios: short grain 1.2, long grain or basmati 1.5, brown rice 2, rice cooker with short grain 1.0.
- Cooked rice (g) ≈ rice (g) × 2.3.
The ratio is by volume, not by weight. Water is given in millilitres, which for water is the same number of grams.
The principle
Raw rice is mostly starch. When heated in water above roughly 60–80 °C, the starch granules absorb water and swell (gelatinisation), so the grains soften and grow. The water you add has to cover what the grains absorb plus what evaporates during cooking. Long grains and brown rice need more: brown rice keeps its bran layer, which slows water entry and requires longer cooking, so more water boils off. A rice cooker has a tight lid and loses little steam, which is why its ratio is lower. Weighing is more precise than scooping because grains pack differently in a cup, and the 0.8 g/mL density lets the calculator translate between the two.
Worked example
- Inputs: 300 g of rice, short grain (ratio 1.2).
- Rice volume = 300 ÷ 0.8 = 375 mL.
- Water = 375 × 1.2 = 450 mL.
- Cooked rice = 300 × 2.3 = 690 g.
- Check: 300 g rice + 450 g water = 750 g in the pot; about 60 g leaves as steam, leaving 690 g.
| Rice (g) | Water (mL) |
|---|---|
| 75 | 112.5 |
| 150 | 225 |
| 225 | 337.5 |
| 300 | 450 |
| 375 | 562.5 |
| 450 | 675 |
| 600 | 900 |
How to read the result
Treat the water amount as a starting point and adjust by 5–10% to taste: less for firmer sushi rice, more for softer rice. New-crop rice holds more moisture and needs slightly less water; soaked rice also needs a little less. The cooked weight helps with portions: a typical bowl of cooked rice is about 200–210 g, so 690 g serves roughly three people. The 2.3× factor is an average for white rice; actual yield depends on the ratio and on how long the pot is left uncovered.
Common mistakes
- Using the weight ratio instead of the volume ratio (1.2 kg of water per kg of rice is not the same as 1 : 1.2 by volume).
- Following the rice-cooker ratio in an open pot, which leaves the rice undercooked.
- Measuring after rinsing without draining well, so extra water clings to the grains.
- Applying the white-rice ratio to brown rice.
Frequently asked questions
Should I rinse rice before cooking?
Rinsing removes loose surface starch and gives less sticky grains; most short-grain recipes call for it. Enriched rice loses some added vitamins when rinsed.
How much raw rice per person?
About 75–100 g of raw rice per person is common for a side portion.
How much less water for soaked rice?
Soaked rice has already absorbed some water, so reduce the amount slightly and adjust after the first batch.
Sources: Harold McGee, On Food and Cooking: The Science and Lore of the Kitchen, Scribner, 2004 (chapter on grains)