There really a simple solution. Measure the rice volume. Wash and rinse your rice. Place it into a large pot. Fill pot with water to equal three times the volume of the rice, i.e. 1 cup of rice to 3 cups of water.
A rice cooker is designed around using twice the water volume, compared to the rice. That is enough water to completely hydrate the rice during the cooking time. The method I'm suggesting uses time to gauge the proper hydration of the rice, and is the preferred method as any excess water is drained off, carrying with it any heavy metal, or pesticide residuals that may contaminate the rice.
Bring the water to a boil, cover the pot, and reduce the heat just to maintain a low boil. Cook for 30 minutes, then drain through a fine mesh seive. Your rice will be cooked through, and be healthier to eat. If you want your rice to have a bit of tooth, reduce the cooking time by seven minutes or so. If you want it very soft, increase the cooking time by another 7 to ten minutes.
No guesswork required.
Oh, and season the water with salt.
Seeeeeya; Chief Longwind of the North