[iainmerrick]

Huh, OK!

I'm surprised that there would be significant evaporation loss in a pot with a close-fitting lid for 20 minutes on low heat. If you heated the water on its own I wouldn't expect a large amount to boil off... Although now I say that, I'm not so sure, maybe I should run that experiment.

I would have guessed the imprecision of 'knuckle depth' being uncalibrated with the volume of rice and the size of the pot would be greater than the imprecision of a pure volume ratio due to evaporation, but I can see that the knuckle depth thing might make sense if you're always cooking roughly the same amount of rice in roughly the same size of pot.

I've had good success cooking rice by the 2:1 ratio in both large and small amounts in various pots, so I'm still happy to vouch for that method.

[Omin]

Another aspect is that there is a large span in the amount of water you can let the rice absorb. A 1:1 ratio of water to rice (not accounting for evaporation) is all you need to cook rice no matter if it's short grain or long grain, but a lot of rice will also happily absorb more, like 2x its weight, if you give it enough water and time. It sounds like you are using long grain rice given the large cooking time and high water ratio.