This is the type of question that would benefit greatly from an example. You haven't provided enough information to really come up with a good answer. That said, here's one way that may give you some ideas:
| A | B | C | D | E | F | G |
---|
From | To | Time | Conversion Table | | | | |
B | C | From Product | To Product | Time | | | |
A | B | | | | | | |
A | C | | | | | | |
A | D | | | | | | |
B | A | | | | | | |
B | C | | | | | | |
B | D | | | | | | |
C | A | | | | | | |
C | B | | | | | | |
C | D | | | | | | |
D | A | | | | | | |
D | B | | | | | | |
D | C | | | | | | |
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[TH="width: 10px, bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]C2[/TH]
Presumably, you have drop-down lists in A2 and B2. The table in E:G shows the amount of time to convert from one product to another, and the formula in C2 will do the lookup. Hope this helps.