I suppose it depends on the type of granite and what quarry it came from but most of the slabs we looked at were something on the order of 6'x10'

See for yourself. Gently lay one on top of the other, then get out your seismograph and wait for the action. :-)
[I couldn't resist.]

florantha:ROTFLOL!!

If I could stop LOL, I'd second willtv. :) Slabs do come in different sizes depending on the quarry, but they typically are 10' long.

Generally, the short dimension is between 5 and 6' and the long one is between 8 and 10'. The range depends on the type of stone and the quarry so you will have a wider choice if you can use 5 x 8 than if your job needs 6 x 10.

The stone we really liked usually comes in smaller slabs - the first ones we saw were 4.5' by 5.5'. The slabs one other store in our area that had the variety were 5.5' by 8'. They checked their other yards and found 5' 4" by 10' 4" slabs in one about 120 miles away. They moved the lot to the local yard so that we could see them. That's what we bought - it allowed us to have only one seam in our L.

We were told that they almost never see slabs that large in our stone.