Somewhere in the software that came with your scanner is a place to set the resolution (Dots Per Inch) of the scan. If you use 100 dpi, your chips will show at (approximately) actual ize on most viewers monitors. If you use 150 (the resolution I usually use), they will be approximately 50% larger than actual size on the screen.

I say approximately because it depends on the physical size and resolution of the monitor of the viewer.