Yeah, he's pretty big....I'd say about 7 inches or so. Funny thing is, you can't normally see his tiny teeth, just the bony ridge that nips algae. I got a big kick out of it when I snapped that close up and saw his teeth!!
My crab didn't used to be such a bright red, but after I moved him to a reef and started dosing trace elements and calcium, etc., he really turned brilliant red.