Grip size of hand and grip size of racquet question

It just occurred to me that in finding your ideal racquet which would include the proper grip size, it seems as if you measure your grip using your ring finger to the second horizontal crease of your palm that you should choose one grip size lower from that measurement. The reason? The buildup from the replacement grip and over grip will increase the grip size by one. So on a L3 frame (4 3/8) the buildup will be to L4 (4 1/2) because of the two grips. Is this correct? The measurement of your hand should be the total size including the grips?
 

golden chicken

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In theory, yes.

In some practice, no. For example, my Wilsons actually measure out correctly at 4 5/8 WITH an overgrip.

Also, if I were to adhere strictly to the rule, I should be playing with a 4 1/2, but I can play well enough with 4 3/8 up to 4 5/8 and I prefer 4 5/8.
 
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