What size spanner or socket does a 9/16" bolt take?
Answer
A 9/16" hex bolt takes 13/16 in across the flats — spanner or socket, and the same for its nut. A socket-head cap screw of this size is uncommon.
How it is worked out
- Spanner / socket — across the flats of the head
9/16" → 13/16 in - Hex (Allen) key — socket-head cap screw
9/16" → not a standard size - The nut takes the same spanner
13/16 in fits the 9/16" hex nut too
A standard hex is about 1.5x the thread diameter across the flats; the exact figure is fixed by the standard, not the formula
Worth knowing
- Spanner size (across flats)
- 13/16 in
- Socket size
- The same as the spanner — 13/16 in.
- Hex (Allen) key
- A socket-head cap screw is not a standard item at this size.
- The nut
- A standard 9/16" hex nut takes the same 13/16 in.
- This is the head, not the thread
- The spanner fits the head. What the bolt threads into is the tap drill, and how hard to do it up is the torque — both linked below.
Spanner and socket size — nearby sizes
The rest of the job at this size
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