A3	11-3/4" x 16-1/2"	297 x 420 mm
A4	8-1/4" x 11-3/4"	210 x 297 mm
8x10 8" x 10"  203 x 254 mm


dot pixels calculation

W=format.w/pen_size
H=format.h/pen_size

so

W= 203/0.3 = 676 
H= 254/0.3 = 846