When I was still working in staging, I got a pair of Steel-toes from Sears (having endured multiple instances of 500+ lbs. being 'set down'--i.e., dropped--on my toes). Problem is, they only went up to a size 12, while I normally wear a size 13. By the end of that gig, some months later, I had damaged the nerves in my big toes to the point that they were continually numb and slightly indented. It took, literally, two years for this to correct itself.
I would suggest going a size larger than you normally wear, if you can stand it and it won't give you hideous blisters. Remember, steel-toes WILL NOT STRETCH!!
If they are at all uncomfortable when you try them on, DON'T BUY THEM!! They will remain at least as uncomfortable.
Also, be aware that 'Steel-Toed' does not imply 'invulnerable.' One of my coworkers caught a 600 lb. road crate that fell off the back of one of our semis, on his foot. It was EXCEPTIONALLY educational to watch at the hospital as they frantically looked for a tool that could cut through the steel toe-cup that had gotten crimped down around his toes like a bottle cap. In the end, they just deadened him from the knee down, and went at it with the saw they used for removing casts and a pair of tinsnips that they borrowed from a workman on the site. Tore him up nicely, in addition to the various bones he broke originally. So consider that a steel-toe is, figuratively speaking (and sometimes almost literally) a double-edged sword.
My $.02, adjusted for inflation.