Measure the water. Most rice cooker instructions recommend cold water. How much water you add depends on what kind of rice you’re cooking and how moist you prefer it.
There are often graduated marks on the inside of a rice cooker, indicating how much rice and water should be added, or instructions on the package of rice. Alternatively, use the following suggested amounts depending on your variety of rice, but keep in mind you can always adjust these in future if you prefer your rice more chewy or soft: