Anyone know the basics on measuring for a picket fence? To dig the post holes do you measure from the center of the hole to be dug? How much wider than the post do you make the hole? How deep and what is the typical height of a picket fence?

Are you buying pre-made sections or building it from scratch?
You measure holes and anything from the middle.
Height is totally up to you - what's the fence for? A 'friendly' fence might be 3' high. It won't keep deer out of your garden or be legal around a pool, etc.
Depth of the holes will depend on the soil, the height and weight of the sections, and how far apart they are, so I would ask the people at your local lumberyard about what is standard where you live and for what you want to buy.
The holes just need to be wide enough to get the post in, rarely that simple with rocks in the way.
Don't let anyone tell you to put concrete around the posts.

No concrete? How do the posts stay sturdy? This is for a front yard. Doesn't need to keep anyone out. Just has to look pretty and maybe tell neighbors to stop pulling my plants out. Yea, I cought a couple of neighbors, not happy with just the flowers, they wanted th bulbs too.

Ack,
Steph

Concrete has been proven to merely rot the posts. You make them sturdy by tamping down the earth firmly around them.

Put about 2'' gravel in hole before setting posts. This will help drain water away from bottom of post.

If setting post in just dirt, about 1/3 of post should be in ground.

If setting in concrete, trowel concrete so that it slopes away from post.

Chuck