#1 is more than NEC calls for. If you have a 200amp panel in the house
and want to run a 100amp sub panel, you will need to run #2AL or #4
Copper. You will find that the Aluminum is much cheaper. I am doing
the same thing. All I really needed was 60amp service to the garage,
but it turns out cheaper to run a 100amp service based on wiring
costs/availability. #6 copper is way more expensive than #2 AL. You
will also need a grounding rod most likely. You should contact the
inspector to see if there is anything specific required in your area.