Metric Hex Bolt Head 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.

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