www.newbalance.com trail runners
Get to know this site, then you'll have to experiment and find out which Last size you need.
Once you find the shoe last that works for you, new balance lists them, like PL-1, RL-3, etc, you can fairly well assume any other shoe made with that last will more or less fit you.
As far as I know, new balance is the only company out there to offer something this clear and explicit.
(tried to hyperlink that one but bpl forum software remains totally broken re hyperlink handling... this isn't hard to fix guys....)
for example, this is the PL-1 last, then it is just a question of finding the last and the width that actually fits your foot. And comes in your width and size .
Note that the lasts are very different, and you might find that one last is narrow, and doesn't require a B size width, while another is wider, and does.
new balance shoe last descriptions
I was lucky and found a variety of trail runners and hiking shoes at the flea market that were barely used, in my size, so I could check out some of the lasts and sizes without losing too much money, unlike in the past.
I also have horrible sizing issues, was my top, number one problem backpacking in the past, and is why I had to not do longer trips, could never find boots that fit, women's, men's didn't matter. For me, this is the actual real reason I wanted to get into ultralight, the idea of actually being able to be comfortable re shoes was so appealing. And it works.
At shopnebalance, you'll need to look at the newer shoes to find the full range of widths.
Do not trust the men's to women's conversion, that varies widely, I know, I've also done the bounce between men's and women's, and the sizes are not consistent between brands and models re men's and women's, you have to find the specific brand and model, then see how that specific ones works.
Also consider sock thickness, with thick smartwool type socks, for example, the PL-1 last, like in the 814 shoe, fits ok, but the RL-3 is a bit tight, but the rl-3 fits like a glove with thinner socks. And consider what others, Roger for example, note, you need a bigger size than you'd think due to expansion of your feet over a day. This is something I found the people at the shoe stores completely oblivious about, for them, a running shoe should be a fairly snug fit, but for backpacking, you need to figure out the sizing and fit yourself and ignore the clerks, unless they happen to do ul backpacking and understand what you are actually going to use these for.
You will be amazed at the difference between using trail runners and boots. I was a bit skeptical of this, so my first lighter trip I used regular low top hiking shoes, which were really nice, but trail running shoes are even nicer.