metric to english conversion

[John Carri]

>what is the correct shade tree english to metric conversion?
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There are 25.4 millimetres to an inch.  Some of those inch- millimetre 
"equivalent" sizes listed earlier are close, but not exact:

Inch size   closest metric size    exact metric size
7/16              11                   11.1125
1/2               13                   12.7
5/8               16                   15.875
7/8               21                   22.225

As you can see, sometimes those "equivalent" sizes are significantly 
off, maybe enough to round off the head of a bolt. If high torque is 
involved, it's probably best to stick with the correct metric or 
english socket.

I grew up outside the US, with the metric system, and I can't believe 
how hard we make life for ourselves here in the USA by sticking to the 
English system, which even the English don't use any more! 

-John Carri