Those fuckers are big. 18-24 inches across, right, Ernest? Or is it 36-48 inches? I forget.
Actually, they just seem bigger than they are. The largest I've seen had a body about an inch and a half wide and about three inches long, but with spread legs they go out to about six inches. They do seem huge if you're used to much smaller spiders.
In general they aren't dangerous to humans. just watch out if they rear back on their hind legs and wave their front legs in front of them. Over the years I've moved hundreds of them out of the house, my usual method involves a jar about eight to ten inches across (a small ice cream tub is also a good option but you can't watch them with that) which I place over the spider on the wall or floor, then slide a large sheet of cardboard under the jar, hold cardboard in place while you carry the spider outside, across the road, and place on a tree.
One time I did frighten a friend of my sisters, I gave her a lift home to her place after their basketball game finished at 11.00 p.m., and a large huntsman had set up a web across the three foot wide path to the front door between the tall hedge and the shrubs in the house garden. When she screamed (she's a bigger arachnaphobe than I am) I got out of the car to see what the problem was. Seeing it was a huntsman I put my hand on the web with my fingers spread and waited for the spider to climb onto the back of my hand, then I lifted my hand off the web, walked across the road to tree, put my hand on the tree, and waited for the spider to walk off my hand when I stopped moving on him. No fuss, no problem.
I'm scared of spiders, but not huntsman spiders - I don't know why.
BTW: Don't go near any that are outside on the ground. Many a person has confused a funnel web spider on the ground for a huntsman on the ground - and they're very dangerous and volatile.