Cable length's

OK....silly question I know because even though I'm asking it, I will measure before purchasing but the background first. I need new inter-connection battery cables. I have (6) 6-volt batteries in a typical configuration (3 set's)....is there a length that is also typical of these wires. There is the three shorter lengths between the + and - and then the four longer ones between the outside terminals of + and -. I see some companies sell 6" and 12" lengths and I'm thinking that sounds right but when you are ordering 2/0 or 4/0 cable..I want to be sure. I was set to order wire, crimps, heat shrink from Amazon but it seems I can get them made for less.

PS...only reason I'm asking is that I don't have access to the batteries here at home.