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Perhaps more so than with any other piece of gear that Better Trail tests, finding the right fit for your ski boots is essential. Backpacks? You can make a bunch of adjustments on the fly. Hiking boots? Fit is important, of course, but they cost a whole lot less. But given the amount of money you’ll pour into a good pair of ski boots—and the amount of time you’ll spend in them—it’s extremely important to make sure they work for your foot shape and size. We won’t mince words: Foot pain due to an ill-fitting ski boot is the worst. Here’s all the information you need to avoid that by dialing in the perfect fit.
How Ski Boots are Fitted
First things first: You should seek the guidance of a bootfitter to size your foot, as well as recommend a few models that will suit you. Bootfitters possess a wealth of ski boot knowledge, and they have the tools to take foot measurements that would be difficult for you to do at home. Most ski shops will have at least one bootfitter; seek them out, tell them what you’re looking for, and they’ll get you underway.
The first thing the bootfitter will do is measure your feet. The process will be a bit more involved than if you were shopping for sneakers: The bootfitter will measure your foot’s length, of course, but they’ll also record the width, your arch height, and your foot’s overall volume. (If you haven’t guessed already, we should probably note here that you should block out a chunk of time for your bootfitting appointment. Precision shouldn’t be rushed.)
Width is a key measurement in choosing the right ski boot, as different boot models come in a variety of lasts, which is the measurement at the widest part of the boot. Generally, a narrow last is regarded as 96 to 98 millimeters, a medium one is 99 to 101 millimeters, and a wide last is 102 to 104 millimeters. (You might see these categories referred to as “low-volume,” “medium-volume,” and “high-volume,” respectively.)
It might seem obvious, but you should target a last that closely matches how wide your foot is. A skier who has a 101-millimeter-wide foot will probably feel cramped in a boot with a 98-millimeter last (like the popular Tecnica Mach1 LV 130), and somebody with a narrow, 99-millimeter-wide foot will have too much room in a high-volume, 102-millimeter-last boot (like the Atomic Hawx Magna). Too tight and you might experience constricted blood flow; too loose, and blisters and a lack of precision while you ski are on the menu. Of note: there are performance considerations that may influence this decision, which we address in the ski style section below.
Mondo Sizing
You now understand the importance of ski boot width, but the number that you’ll probably use to begin future ski boot searches—and the measurement that your bootfitter will probably take first—is your foot’s length. Ski boots use Mondo sizing, which is different from the U.S. or EU sizing that you use to buy hiking boots and street shoes. Mondo sizing corresponds to your foot’s length in millimeters—27.5 Mondo is 275 millimeters, for example.
We want to flag an important point here. If you’re shopping online, you’ll likely come across sizing charts that match standard U.S. shoe sizes with their corresponding Mondo sizes. Take those conversion charts with a grain of salt. One of our Better Trail editors, for example, typically wears a men’s size 9—charts would place him in a 26.5 to 27.5 Mondo—but he consistently ends up in a 25.5 across every brand he’s tried. The takeaway: get your foot measured if you can. If not, try ordering multiple sizes from a reputable retailer and return what doesn’t fit.
With your correct Mondo size in hand (er…on foot?), as well as the other measurements the bootfitter has taken, they can now recommend a few models that might fit the bill. You should take these numbers down for future reference, if you ever want to start the hunt for a new ski boot on your own. We still recommend seeing a bootfitter, though, as they have a vast knowledge of the different lasts, shapes, and quirks of various models, and will help you home in on the perfect boot for your feet and ski style, as well as adjust the boots post-purchase if need be (more on that process below).
Know Your Feet—And Your Ski Style
It’s helpful to the bootfitter (and yourself, of course) if you have a general idea of how your feet feel and work. Are you prone to blisters on your big toe? Is your left ankle a bit wonky? Do you have poor blood flow to your feet, especially in the cold? Any information you can give the bootfitter about your podiatric preferences goes a long way towards picking the right boot, and can save you the pain (literally) of having to deal with an issue that might not be obvious from the raw numbers of your foot measurements.
Similarly, the type of skier you are—or aspire to be—plays a key role in choosing the right boot. Expert skiers who prioritize precision and responsiveness will likely prefer a snug-fitting model with a narrower last that hugs the foot closely and leaves no room for slop. Take the K2 Cortex 130 Zonal Boa we recently tested: despite its 98-millimeter last, it ended up being a great fit for our wide-footed, hard-charging tester—after a few post-purchase modifications (see our Cortex 130 review for more).
On the other hand, newer or intermediate skiers—or anyone who doesn’t plan to be charging hard all day and values comfort above all—may be better off with a boot that allows for a bit more wiggle room. A medium- or high-volume option, like the ultra-comfy Lange Shadow 115 W MV (or the men’s 120 MV version), will likely feel better over the course of a long, bell-to-bell day on the hill.
Calf Size and Cuff Fit
While a ski boot’s Mondo size and last are easy to ascertain, the diameter of its cuff and how tight it closes will require on-the-ground sussing out. Different models, even within a given brand’s lineup, vary in how wide or narrow their cuffs are and how tightly they close around the wearer’s calf.
When you’re trying a boot on, a good bootfitter will ask you how the boot feels around your calf when the buckles (or Boa dial) are tightened to a reasonable amount—not ratcheted all the way down, which would be uncomfortable over the course of a full ski day. It’s also helpful to tell your bootfitter if you have a wide, average, or narrow calf when you start the fitting process, as it will help them zero in on the models that will work best with your body.
Wide Feet
Skiers with wide feet, you have no need to despair. Now more than ever, ski boot brands are producing models with high-volume lasts, which we categorize as 102 millimeters and up. There are high-volume (sometimes noted as “HV”) versions of many models that we’ve tested and enjoyed (and that also come in medium- and perhaps low-volume lasts as well). For example, the Tecnica Mach1 MV 130 comes in a 103-millimeter HV build, and the Atomic Hawx Prime XTD 130 Boa is available in the (non-Boa) 102-millimeter Magna version.
We also recommend checking out K2’s BFC (“Built for Comfort"), which consists of a lengthy roster of boots with 103-millimeter widths. The models range from beginner-friendly boots with soft flex ratings to stiff, burly boots for expert skiers. If you need something even wider, Nordica’s Cruise series might do the trick. All of the boots with the Cruise moniker are 104 millimeters wide, and like the BFC line, they come in a range of stiffnesses. The boots above are just a few of what the market has to offer wide-footed shredders, and your bootfitter will likely have even more suggestions.
How Ski Socks Factor In
When getting fit for boots, wear the socks you intend to ski in. Sock choice is, of course, personal preference, but we do recommend ski-specific socks that are on the thin side. That’s because you want your ski boot liner—either after it’s been molded, or over time if you don’t get it molded—to fit the exact shape of your foot as closely as possible. A thick sock leaves more margin for error (and potential for blisters) during fitting, and it can bunch up and cause additional issues when you’re on the hill.
There are many reputable ski sock brands out there, including Smartwool, Darn Tough, Le Bent, and Lorpen. Ski socks vary in terms of their thickness, cushion—both on the foot and up the shin—and their material composition. We recommend getting a sock that is made of wool, synthetic, or a combination of the two (a personal favorite of ours is Le Bent’s Shred Targeted Cushion, which has a nylon, wool, bamboo, and elastance blend). As with hiking socks, you should avoid cotton, as it does a poor job of wicking away moisture and insulating your feet.
Heat-Moldable Liners
The vast majority of ski boots on the market today come with liners that your bootfitter can mold to your foot, which is a nice way of expediting the fit and comfort process (rather than simply skiing in the boot to break it in). To do so, the bootfitter will take the liners out of the boots and heat them using a specialized device. They’ll then put the liners back in the boots and have you step in (make sure you’re wearing the correct socks, and also have the footbed you’ll be skiing in), tightening all the buckles like you would if you were on the slopes. After waiting a short period of time—usually around 10 minutes or so—you can unbuckle and (hopefully) enjoy a boot with a liner that fits your foot like a comfy glove.
While it’s likely that you’ll only have to do one liner molding session, it’s not a problem if you have to go back to the bootfitter and get them re-molded, usually to address a specific hot spot or two that may have cropped up once you hit the snow. The bootfitter will take care of the problem area, and you can be on your way. (In case you’re wondering, yes, you can technically mold your liners at home using your oven, but this is not the recommended way to dial in your boot fit. You can easily ruin the liner, and going to a bootfitter is a much better choice.)
Finally, if a boot’s stock liner just isn’t working for your foot, you have the option of using an aftermarket liner from a brand such as Zipfit or Intuition. Both brands offer liners in a wide variety of thicknesses, stiffness, and intended use cases (touring-specific models, for example), and are meant to be heat-molded as well. Buying an aftermarket liner is also a great way to breathe new life into a ski boot you’ve had for a number of seasons, after its liner has become packed out and lost some of its stiffness.
Heat-Moldable Shells (Getting Punched)
For addressing specific fit issues, such as a bunion, high arch, or sensitive spot on the foot, you may need to have some alterations done to the outer shell of the boot. Sometimes called “punching out” the shell, this process starts with you and the bootfitter identifying pinch areas on an otherwise well-fitting boot that molding the liner or replacing the insoles (more on this below) can’t fix.
The bootfitter will heat the boot shell in an oven, or perhaps only the targeted area with a heat gun, and then work their magic to give you a tiny bit more space while the shell’s plastic is temporarily malleable. Unlike molding liners, however, there are only so many ways and times you can punch out a shell, which drives home the importance of initially choosing the boot that’s best for your foot. We should also note that some brands make boot shells that specifically ease the punching-out process. Tecnica’s CAS (Custom Adaptive Shape) tech, for example, consists of pre-mapped zones on the boot shell that are dimpled, which makes for easier heating and molding (you can learn more in our review of the CAS-equipped Mach1 boot).
Replacement Insoles
A boot’s stock insole—sometimes called a footbed—may not quite work with your foot shape, or perhaps you want an insole that offers a bit more (or less) arch support. If that’s the case, purchasing an aftermarket insole is an easy way to adjust the boot’s volume slightly and provide a more robust platform underfoot. Going with a trim-to-fit brand like Superfeet or Sidas is relatively inexpensive (Sidas' Eco Winter will run you $55), and the insole will mold to your foot over time. Additionally, there are a number of brands that provide more expensive ($300+ expensive), custom insoles that can be molded to the exact shape of your foot.
Boa vs. Buckles: Adjusting Your Fit on the Fly
Even after you’ve chosen the ideal ski boot, you’ll still have to make sure that you properly adjust your boot when you’re actually skiing. This means making the boot tight enough that it responds to your input the way you want, but not so tight that you’re cutting off blood flow and walking around in pain. Modern ski boots have two adjustment mechanisms: buckles and Boa systems. Buckles are the traditional method for tightening your boots, and consist of a latch (either metal or plastic, but hopefully metal) that you secure via a series of ratchets on the boot’s shell. Some boot buckles also have the ability to make microadjustments to the latch, which helps fine-tune the tightness. Buckles are simple, intuitive, and easily fixable.
Over the past few years, more ski brands have begun outfitting their boots with Boa systems. A Boa consists of a dial, either on the cuff or the forefoot—or, in the case of the K2 Cortex 130 Zonal Boa and the Salomon S/Pro Supra Dual Boa 120, both—that is attached to thin steel cables that run through the boot’s shell. Tightening the Boa dial in turn tightens the cable, which tightens the shell. The main benefits of a Boa system are that the dial has a higher, more precise number of tightness settings than you get with buckles, and that the wire, ideally, spreads pressure more evenly across your foot. A Boa dial is also often quicker and easier to operate while you’re wearing gloves, and you can loosen your boot for riding a chairlift by simply twisting the dial in reverse.
However, plenty of skiers will prefer the old-school reliability, feel—and look—of a boot with buckles. Boots that have a Boa system are typically more expensive as well, with some of the models that we’ve tested edging well north of $1,000. (We’re looking at you, Atomic Hawx Prime XTD Boa.) Choosing between the two will come down to personal preference, but it’s worth taking a look at (and getting a feel for) a Boa boot if you can check one out in the shop.
happy feet, happy skier
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