Excell calculator

When bending sheet metal parts ie a tray (like a shoe box lid) we need to manually select and calculate which tooling lengths will be appropriate for the job. I was looking at the possibility of having a program (can be excel) to do this automatically. Bending a tray we would put the nearest correct amount of tooling into the machine to accommodate the nearest length The tooling is segmented in various sizes so there so they can be mixed and matched to achieve the desired length. What I am looking to do is have a list of all the segmented lengths of tooling in a list, input the required job length and the program will identify which segments of tooling to use. Ie if we are bending 1250mm long, the tooling would be 1off 1000. 1off 250mm. if we have 1240 and there is no match it needs to calculate the nearest which can be smaller but not bigger. Ie 1230 is ok but 1250 is not.