I just threw one on a floor scale for giggles and they were 47 lbs each side. Certainly not as light as a real racing shell seat, but definitely much lighter than stock seats. Hope that helps.
2012 335i Sport, 6 Speed RWD
2006 330i Sport (sold) - 2002 330i Sport (sold) - 1996 Boston Green M3 (sold) - 1995 325is (sold) - 1973 2002 (sold)