Drill bit sizes

[Broadback]

Can some one please help me with drill bit size numbering? I have Googled, but my finds were confusing. Some fitting require hole size in inches, some in mm, ok I can convert those, but others are in Drill Numbers, for example a wall plug may require Drill #10, where can I find these equivalences please? TIA

[John Woodison]

[Andy Wade]

I think he was talking about masonry drills, not the old number-sizes of morse twist drills, to which that table refers.

For masonry drills the following is about right:

No. Dia./mm

--- ---

8 4.5 10 5.5 12 6.5 14 7.0 16 8.0

[Paul Barker]

fixing, 10mm for 10mil frame fixing

-- Paul Barker

[Broadback]

Thank you both for taking the trouble to answer. Perhaps you can see why I am confused, how can a No 14 drill in one case be 4.6mm and in the other 7.0mm.

[Christian McArdle]

I just halve them for mm. It's always been close enough for me.

Christian.

[Andy Wade]

For the same reason that 30 SWG wire isn't the same size as 30 AWG, even though they're both "30 gauge" - different scales, historical reasons, "not invented here" and the mists of time. Oh, and to confuse the uninitiated :-)