The M&P 45C is a hair bigger than the Glock 23 in every dimension, essentially the same size though - very close. It is a bit heavier but an empty 23 is a feather. Both fully loaded with 180's and 230's, they're very close with the 23 having a five round capacity advantage. The 45C feels like a more substantial, higher quality gun IMO and I'm a huge Glock fan.