The top plate is 6" x 10" (then add maybe 5/8" on each side for the thickness of the base), and the base is 3-1/2 tall, to which you add the height of the feet -- maybe 3/8" or so.
If you will eventually want to install the speedball upgrade, you'll need all the internal height of the 3-1/2 dimension. Also helps to leave the base full height for large film caps that people often find to be a nice upgrade. The height does not include the tubes or transformer.
HTH,
Jim
