One cup of white rice wants about 1 1/2 to 2 cups of water on the stove, and about 10–15% less than that in a rice cooker. That is the whole answer, and it is also why every calculator you try gives you a slightly different number: they are answering for a different pot, and most of them do not say which one. Below is the conversion table in cups, millilitres and grams — plus what to do when the number you were given still leaves you with a wet or a crunchy pot.
Use the same cup for the rice and the water, and the ratio holds at any batch size. This site uses the US food-label cup: 1 cup = 240 ml. One level cup of uncooked white rice weighs about 180 g, which is what the gram column is built on.
| Dry rice | Stove water | Rice cooker water | In millilitres |
|---|---|---|---|
| 1/2 cup (90 g) | 3/4 – 1 cup | about 2/3 cup | 180–240 ml |
| 1 cup (180 g) | 1 1/2 – 2 cups | 1 1/3 – 1 3/4 cups | 360–480 ml |
| 2 cups (360 g) | 3 – 4 cups | 2 2/3 – 3 1/2 cups | 720–960 ml |
| 3 cups (540 g) | 4 1/2 – 6 cups | 4 – 5 1/4 cups | 1,080–1,440 ml |
| 4 cups (720 g) | 6 – 8 cups | 5 1/3 – 7 cups | 1,440–1,920 ml |
The pattern to keep in your head is two rules, not a table. Stove: water is roughly double the rice. Cooker: start from the stove number and take off about a tenth to a seventh. Everything else is arithmetic on those two.
This is the part no calculator tells you. Enter one cup of white rice into the tools that rank for this search and you will be handed 1:2 by one, 1:1.5 by another, and 1.75 by a third — for the same rice. They are not each other's typo. They are three different sets of assumptions, and only one of them writes its assumptions down.
| What it assumes | What it gives for white rice | Who says so |
|---|---|---|
| Stove, fixed ratio by grain | 1:2 | only one of them states "assumes you are using a stove" |
| Rinsed rice, at sea level | 1:1.5 | the one that prints its assumptions also prints a ±5% correction for unrinsed rice or high altitude |
| Same table as the 1:2 group | 1:2 | not stated — the number simply matches the other one |
Three things move the number, and a calculator that does not let you set them is picking for you:
None of the three makes the others wrong. It means a single number detached from its assumptions is not an answer — it is a guess with a decimal point.
Here is the trap for anyone cooking by weight, and it catches people who switch from a cup recipe to a scale. 1:2 by volume is not 1:2 by weight.
A level US cup of uncooked white rice weighs about 180 g. A US cup of water weighs about 240 g. So the "one to two" you have been using all along is, once you put it on a scale:
180 g rice : 480 g water = 1 : 2.67 by weight
That is not a contradiction, it is just two different measuring systems, and this is why a European recipe written in grams will not match an American one written in cups even when both claim the same ratio. If you weigh, weigh. If you scoop, scoop. Do not run one number through the other system.
Going the other way is the same arithmetic flipped: water in grams = rice in grams × 2.67 for white rice on the stove. For 100 g of rice that is about 267 g — which is also the same as 267 ml, because water weighs a gram per millilitre. That is the whole reason weighing is easier once you have done it once: the water number and the volume number become the same number.
Pour in two cups and cook a cup of rice, and you do not end up with three cups of anything. Part of that water boils off through the lid during the simmer, and the rest is inside the grain rather than sloshing around it. Cooked rice is roughly two-thirds water by weight, which is where the absorbed portion went.
This is the reason "I used the calculator and it still came out wet" has an answer that is not the calculator's fault. The tool assumed your lid fits the way theirs did and your burner runs at the heat theirs does. Both change how much of the water leaves during the cook. The ratio gets you into the right neighbourhood; the last quarter cup is yours to nudge.
Two failures cover almost every bad pot, and they pull opposite levers.
And one step that is not on any calculator: when the water is gone and the heat is off, leave it covered for 10 minutes before you open it. The rice is still finishing during that rest, and it is the step that turns a correct ratio into separate grains.
1 1/2 to 2 cups on the stove; about 1 1/3 to 1 3/4 in a rice cooker. Use the low end if you rinsed and drained the rice, the top end if it went in straight from the bag.
3 to 4 cups on the stove. In a rice cooker, take 10–15% off that: about 2 2/3 to 3 1/2 cups.
They are answering for different setups. One is built around the stovetop; the other assumes rinsed rice at sea level and prints a 5% correction for when that is not true. Neither is miscalculating — they are just not telling you the same story.
No. 1:2 by volume works out to about 1:2.67 by weight, because a cup of rice weighs about 180 g while a cup of water weighs about 240 g. Pick one system and stay in it.
About 267 ml on the stove (100 g × 2.67). Water weighs a gram per millilitre, so the gram figure and the millilitre figure are the same number — which is the one nice thing about weighing.
Yes, roughly 10–15% less than the stovetop number. The cooker seals in the steam the stove loses, so that steam goes back into the rice instead of out of the pan.
Yes, by a visible margin. Rinsed and drained rice carries its own film of water into the pot, so it needs the low end of the range.
One cup of rice to 1 1/2–2 cups of water on the stove, about a tenth less in a cooker, and the same cup on both sides of the equation. When two tools disagree, they are disagreeing about your pot, your rinse and your altitude — not about arithmetic. Set those three and the number stops moving.