formula or software

[chimichanga]

I feel really dumb but is there a formula or software for figuring out how many certain size hole can fit in a sqare area? I'm trying out find out how many 1/2" holes I can make inside a 21"x 9 3/4 " plate.

any help would gladly be appreciated.

[timrb]

If my AutoCad Fu is okay, I make it about 45 by 19 half inch holes. But that's packing them with zero space in between.

Tim