As will tooling selection...Grade will make a huge difference.
Susssh . . . don't tell all the CAD jockeys that have never seen a press-brake, box and pan or even a vice and hammer that . . . it means all that time they spend creating a layout that the fabircator ignores will be wasted . . .As will tooling selection...
The best thing to do is a few test bends. Cut a piece at a known measurement, 100.00mm, then bend it with the intended tooling. Measure each leg accurately to work out your bend allowances, your k factor can then be worked out from that
I did a stint of precision sheet metal a while ago, working to 0.1mm usually. More often than not, the computer dimensioned pattern didn't quite work out, so you'd use a baggy vee to form to gain a little extra material.