I do mine across the belly-button (good reference point, it does not move much). I think the most important thing is to be consistent. I have been tracking my waist measurement in a notebook over the past few months. Its kind of nice to be able to see how it changes (shrinking so far, knocking on wood!). A few weeks ago I found a free tracker at www.webfitnesstools.com, kind of cool (graphs it out and stuff).

The narrowest point of my waist is a good couple of inches higher than my belly button, so that's where I measure. My waist is 31", but if I measure across the belly button it jumps to 36". I know which number I prefer! LOL

Whodathunk finding your waist would be so dang complicated?! LOL

I have always considered my narrowest point to be my waist. For me, this lies below my bottom ribs and above my belly button.

Good luck with the search!
ABBA

I guess that if you're male and overweight witht the weight usually around the belly then if you wear low waist jeans, of course the jean size will be smaller than your actual waist size.. I think that's why you measure your waist at 46" but wear 38" trousers. o_O
Being a female, it's my hips that count most for trouser size, my waist is a 25-26inch (before or after lunch) but I wear 27-28" trousers because of my hips that never fit in smaller jeans! snif snif