Metric Bolt Head/Wrench Size

Bolt Diameter
(mm)
Head/Wrench Size
(mm)
ANSI/ISO DIN JIS DIN/ISO
Heavy Hex
4 7 7 7 -
5 8 8 8 -
6 10 10 10 -
7 - 11 - -
8 13 13 12 -
10 16 17 14 -
12 18 19 17 22/21*
14 21 22 19 -
16 24 24 22 27
18 - 27 - -
20 30 30 - 34/32*

ANSI - American National Standards Institute
ISO - International Organization for Standardisation
DIN - Deutsches Institut fur Normung
JIS - Japanese Industrial Standard
* Indicates ISO standard.