If you want to buy it at a store, try one on, and if it fits, buy it. ( self explanitory ). LOL!  Now, If you want to buy it online, go to the nearest store ( target, meijer, timberland, any mall, etc. ) and try on a pair, and if that one fits, go home, and buy that size online.  EXAMPLE: Go to a store and try on a size 11 ( or other ) and let's say the size 11 fits, you go home and buy that size on there website: http://www.timberland.com/home/index.jsp . :D                           If you don't want to go to the store for that, you can think of an old pair of timberlands you have that don't fit anymore, and probably get one size bigger than that. You could also go and see what size you are on one of the foot measure things. HINT/TIP: usually, shoes online are cheaper than ones at the real store. * HINT HINT * ;]         I hope i helped!