Buying boots online is very difficult because there is no standard and consistentancy in the numbers. EXAMPLE: Just because you are a size 9 shoe, you will see many charts saying that you should be in a 27.0 (2+7=9), first for the most part, no boot manufacturer makes a 27.0, they simplified SKU's and offer just a 27.5 which really is the same as a 27.0 in shell size, it was just a slight liner insert that was the difference between the two sizes. Thats just the start, most people with that size 9 will actually be professionally fit in a 26.5 shell and some that are looking for a more performance fit, might even drop to a 25.5 shell. Shell length is just the start, you will then see numbers like 97, 98, 100, 102 and 104 being thrown around, these are published widths. Not only is there not a standard here, how it is measured is also a big variable. What is overlooked is this is the easiest area to make accommodations to the shell and fit, but that is a topic for it's own discussion. Next is how does the heel/ankle area fit the foot, are the boot and the foot matched in shape and volume? No way to know this when looking online. Now flex, another area that there is no standard not only between brands but also models within brands. Lastly, footbed and a proper ski sock, something that most people who consider buying online do not consider. When the average person who skis (note, I did not say "skier") buys a boot online, opens the boot box, grabs their favorite (thick) hiking sock and puts their foot into the boot, immediately thinks "too small". Well, strike ONE: Wrong sock. Strike TWO: No footbed, Strike THREE: The foot is not competely in the boot, the boot needs to get the boot buckled and the heel INTO the heel pocket. All of this before even considering if the boot is even remotely close to being the right boot.
@clewis This is not just for you, but it is a question that is asked by more than a few thousand people every season and it needs to get addressed constantly.