Im not sure its just me or someone else have the same problem also...
Sprouting 800.000 beans , my rig is online 24/7 , my connection to the network is over 30 all the time, sometimes 65,sometimes 35.
Last time i received sprouts it was 2/27/2018 , now im close to 50% result what the  online bean cash calculator estimated.
I never believed any online coin calculator in the past, those calculator are just a rough estimate... but none of those calculatros are 50% off ...