I came up with this procedure which has served me well for years, with minimum hassle:
1) Measure X volume of rice (100ml, 3.14159 fl oz, your favorite Hello Kitty mug, whatever unit works for you) in a pan.
2) Wash the rice as usual, drain excess water, leave the rice on the bottom of the pan
3) Add just enough water that the surface of the water equals the surface of rice, no less, no more
4) Remember the volume of X? Now add exactly this amount of water.
5) Cook as usual: lid on, maximum heat until it's almost starting to boil, minimal heat for 7-8 minutes which just barely keeps the water boiling, then heat off for 7-8 minutes, do not open the lid after the first few minutes.
Seems to work every time across different pan sizes and different amounts of rice being cooked, unlike some weird rules of thumbs based on the height of water in pan above the rice surface.