Don't know of a list to hand, but for STANDARD Allen bolts / capscrews, a rough rule-of-thumb is the Allen key size will be near tapping drill size, and from that, the screw size can be decided:
3mm key - M4
4mm key - M5
5mm key - M6
6mm key - M8
8mm key - M10
10mm key - M12
The other parameter then is length, which can be checked with a rule or tape measure, eg M6 x 20mm, M8 x 35mm.
Note a) this rule-of-thumb doesn't necessarily apply to other Allen-type screws (eg, the big domed "button head" fairing screws, and b) there are also "metric fine" threads with a slightly different thread pitch (although I've never known them used on ordinary screws).
The above list should see you right.