Imperial self tapper size number compared with metric equavilent conversion in mm
 METRIC CONVERSION TABLES.  
Self Tapping Screws.


Also information on Imperial/Metric Conversion Tables ;
SI Unit Descriptions ; SI Derived Units - in terms of SI Base Units
and the SI Prefixes (giga- , etc.).

Imperial Self Tapper
Size No.
Metric Equivalent
mm.
2
4
6
7
8
10
12
14
2.2
2.9
3.5
3.9
4.2
4.8
5.5
6.3
Imperial Self Tapper
Size No.
Metric Equivalent
mm.


We have tried to be accurate with the above table but cannot be held responsible for in-accuracies.
Go back to first principals and double check your calculations if the result is 'mission critical'.
Even the brilliant brains at NASA have made a conversion error or two !

More information on the SI System (Le Système International d'Unités) base units and definitions.