Newbie boarder or skilled bonkin-gibber, your boots will have the most dramatic impact on your freeriding performance and enjoyment. The goal is to find a balance between a snug fit (performance) and relaxed fit (comfort). Here are some guidelines that are important to consider at any skill level:
Regardless of whether you're a beginner or expert boarder, you will want to downsize a half size from your normal shoe size to the equivalent Mondo (i.e. 24.0 vs. 24.5) size on the chart. Advanced boarders know that a snug fit means performance. One way of increasing sensitivity to the board and enhancing performance is by buying your boot one full size smaller than your measurement. Think carefully about following this path, however. If you're intending to downsize you should be prepared to customize your boots as needed to balance fit with comfort. The snowboard boot is a seem-ridged environment that can be adjusted and customized, but there are general limits of a half size of stretchability for a too restrictive/uncomfortable boot selection. With that in mind, consider that a customized footbed can greatly enhance the fit of the boot you select. Footbeds add support, give more effective toe room, snug up width, and tighten up foot steering performance.
When you try on your snowboard boots wear a thin to mid-weight wool/wool mix sock ---- one pair only. The padding of the inside liner of your boot, is an open-celled foam designed to compress and stretch to some degree to fit your feet, so expect your boots to loosen up a bit through use. Wear your boots around the house for a couple of hours intermittently to pre-adjust them before your first mountain session. Note that your boots will fit best when flexed ... snug and comfortable in the heel through forefoot with a little wiggle room for just your toes ----- this is the position you'll be riding in. When you stand up with your knees straight your toes will just brush the front of the boot liner.
All boarders recognize that it takes three to four days before boots complete their break in process. Be prepared with alternative socks of varying weights in order to adjust for subtle boots changes. Keep in mind that fit and comfort starts next to the foot and moves out through the liner from there. Selecting a good feeling sock makes a world of difference in fit and comfort. A common choice is to combine a light liner sock with a snowboard-specific, light- to medium-weight merino wool (avoid cotton).
If you are a woman, you'll be happy to know that snowboard boots specifically designed for women, use women's specific lasts. Women's boots tend to have narrower heels, a higher arch, and are cut a bit lower.
Type of Boot
Selecting a snowboarding boot also depends on what kind of riding you are into. All mountain riding requires a stiffer boot. If you're a larger, heavier, and/or more aggressive rider you'll also want a stiffer boots for greater control. If you're into performing tricks, lighter in weight, or a slower rider you'll prefer a soft boot.
In general, snowboarding boots are getting stiffer as snowboarders continue to ride faster, jump bigger, and do harder tricks. A stiffer boot helps support the impact on jumps and keeps the board under control. Consider purchasing a stiffer boot no matter what.
If you are buying boots for feet that are still growing, resist the temptation to buy "boots to grow into." It is reasonable to "buy up" one boot size for growth, but anything beyond that compromises the fit necessary for ease of learning. Remember the boot has a huge impact on boarder fun, comfort, and effort. If you do go oversized the key is minimize heel lift. Wearing two pairs of socks with an oversized boot usually does the trick in snugging up the fit.