Well, 10 to 12 cm is a pretty nasty size for a spider. We got one particular web-spinning species in my area whose specimen can get almost that big. Most of them are about 7 or 8 cm. But once in a couple of years you come across one that is as big as the palm of your hand (about 10-11 cm), which happened to me not even a month ago. I was sitting at my desk, raised my head to think and there she was, sitting on one of my scripts about three feet away, staring me right in the face. The first moment was so bizarre, I didn't even get it, that there was actually a huge spider sitting on my papers, till I caught myself making some stupid sound like a "moooh". Normally, when a spider realizes she has been spotted, she runs. This bastard however was so big, she just didn't care. She just kept watching me, how I took off my shoe and circled around to the side next to her to smack her over the head. Strange moment.