Ever wonder what the size number for rebar represents? It's actually quite easy. The number represents a unit of 1/8 of an inch. So that means a #4 rebar is 4 times 1/8" or in other words - 1/2". #5 bar is 5/8"; #6 bar is 3/4" and so on. To cut and bend your rebar, check out the rebar cutters and rebar benders at Fascut Industries.