METRIC CONVERSION TABLES.  
Metric Threads


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.).
 

Thread Size
 Pitch
mm
Tapping Drill
Size  
 Clearance Drill
Size  
ISO
Spanner
M (= mm)
 Coarse
 Fine
 mm
 mm
 mm
1.6
2.0
2.5
3.0
3.5
4.0
5.0
6.0
8.0
10.0
12.0
16.0
20.0
24.0
 0.35
0.40
0.45
0.50
0.60
0.70
0.80
1.00
1.25
1.50
1.75
2.00
2.50
3.00
-
-
-
0.35
0.35
0.50
0.50
0.75
1.00
1.25
1.25
1.50
1.50
2.00
1.25
1.6
2.05
2.5
2.9
3.3
4.2
5.0
6.8
8.5
10.2
14.0
17.5
21.0
 1.65
2.05
2.6
3.1
3.6
4.2
5.1
6.1
8.2
10.2
12.2
16.25
20.25
24.25
 3.2
4
5
5.5
6
7
8
10
13
17
19
24
30
46
M (= mm)
 Coarse
 Fine
 mm
 mm
 mm
Thread Size
 Pitch
mm
Drill Size
mm.
 Clearance Drill
Size  mm
ISO
Spanner


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 In3.1ternational d'Unités) base units and definitions.