What size spanner or socket does a 5/8" bolt take?
Answer
A 5/8" hex bolt takes 15/16 in across the flats — spanner or socket, and the same for its nut. A socket-head cap screw of the same size takes 1/2 in.
How it is worked out
- Spanner / socket — across the flats of the head
5/8" → 15/16 in - Hex (Allen) key — socket-head cap screw
5/8" → 1/2 in - The nut takes the same spanner
15/16 in fits the 5/8" 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)
- 15/16 in
- Socket size
- The same as the spanner — 15/16 in.
- Hex (Allen) key
- 1/2 in for a socket-head cap screw of this thread.
- The nut
- A standard 5/8" hex nut takes the same 15/16 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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