So i made this MathCAD file with fully planetary gear ratio calculation, all you need is to put the motor name in, put ring gear teeth number (teeth_of_sun_gear + 2*number_of_planet_gear) in, and sun gear teeth number (teeth_of_ring_gear - 2*number_of_planet_gear) in. It will automatically generate 8 kind of situations, with different speed output in rpm.
Bilingual version ! Chinese and English !
Gary from Team 4001