Rice portion calculator
A side portion is about 60 g of dry rice per person and a main about 75 g. Four people need 300 g dry, which takes roughly 450 ml of water by the absorption method and yields about 900 g cooked.
How to portion rice
The water ratio depends on the rice and the method. Absorption cooking of white long-grain wants about 1.5 times the rice by weight; brown rice wants closer to 2.5 and twice the time; basmati does well at 1.5 after a soak. Rinsing matters more than most recipes admit; it removes surface starch, and skipping it is the main reason rice turns out gluey. Risotto and paella are different techniques entirely and take far more liquid, added gradually.
Questions
About 60 g dry as a side, 75 g as a main. It roughly triples in weight when cooked.
About 1 : 1.5 by weight for white long-grain, 1 : 2.5 for brown. By volume it is often quoted as 1 : 2.
For long-grain, yes. Until the water runs clear. It removes surface starch and stops the grains clumping.
Around three times in weight. A hundred grams dry gives about 300 g cooked.
Usually unrinsed rice, too much water, or stirring during cooking. Leave it alone once the lid is on.