One US cup of uncooked long-grain white rice weighs about 185 g, the USDA figure used in the answer box above. The measuring cup that comes with a rice cooker is smaller, about 180 mL, so it holds about 141 g of long-grain rice. With the rounder short-grain rice that most Taiwan and Japan households cook, the same rice cup holds closer to 150 g.
Why the weight depends on how you measure
Rice grains are hard and do not compress, so the filling method matters less than with flour. What matters is the grain itself. Long, slim grains leave more space between them, while short, rounded grains nest together. USDA lists 185 g per US cup for long-grain, 195 g for medium-grain and 200 g for short-grain white rice, and the range above reflects that spread. A recipe written for jasmine or basmati rice therefore uses less rice by weight per cup than one written for sushi rice, even with the same cup.
The Tiger rice cooker guide describes the correct way to fill the cup: fill the cup with rice, then level it off with a chopstick, and do not press it down or shake the cup, because that changes how much it holds. One level cup is one gō (合), 180 mL. These figures are for dry, uncooked rice; rice that has been rinsed and drained holds some water and should not be measured again afterwards.
Which cup does your recipe use?
If you are cooking in a rice cooker, use the cup that came with it, not a baking cup. The water lines printed inside the inner pot are drawn for that cup, so measuring 2 cups with a US cup and filling to the 2 line would leave you with too little water for the rice you added. The Taiwan rice cup is a convention rather than a regulated size, and the Tatung electric cooker manual, for example, measures rice with its own cup without stating a volume in millilitres. Cups can differ slightly from one maker to another.
American recipes that say “1 cup rice” mean the 236.6 mL US cup, which is about 1.3 rice cooker cups. Australian recipes use the 250 mL metric cup. A Japanese recipe may mean either the 200 mL cooking cup or the 180 mL rice cup, so check whether it is measuring rice for the cooker or an ingredient for a dish.
Tips for measuring by volume
- Keep the rice cooker cup with the cooker, and use it for both the rice and the water line.
- Level each cup with a chopstick or knife instead of shaking it flat.
- Measure the rice before rinsing, then rinse and drain it in the inner pot.
- For firmer or softer rice, Tiger suggests adjusting the water within about a third of a cup either side of the line.
- When scaling a recipe from US cups, convert to grams first; 185 g of long-grain rice is not the same as 1 rice cup.