For this kind of spider, only the females get to be this size (males are much smaller). Also, the little red markings are also a female trait.
I knew a guy who had lots of pet spiders. He had upwards to 20-40 spiders. He had a "bird-eating" tarauntula, too! It molted and he brought the 'skin' into the office. It was the size of an average dinner plate!!! he LOVED spiders... the kicker to me was that he has a phobia of storms!!! (I love storms!)
Holy...! Now THAT's a big spider.
Bird eating tarantula, eh? That's just nuts...although I'd love to see it in action.