Ski Boot Sizing & Buyer's Guide (Size, Fit & Flex)
We have one of the largest selections of ski boots on the web, a super knowledgeable staff and expert guides to help you make an informed decision.
Boots are the single most important component of your ski setup, and it’s worth spending extra time and energy to get the right boot with the right fit. Your boots are your only way of translating your body’s intentions to your skis, so a precise fit is important for control and performance. By the same token, ski boot shells are made of hard plastic, so conflicts between the shape of your feet and the shape of your boots can cause fit problems. The goal in ski boot fitting is to find a size and shape that you’ll be comfortable in without compromising too much performance.
Everyone’s foot is unique, and regardless of what some bootfitters will tell you there is no one “right” way to fit boots. The size, shape, flex and features of your ideal boot will vary depending on ability level, aspirations, height and weight, frequency of days on the hill, and other factors. Because of their construction and the job they have to perform, ski boots will never be as comfortable as street shoes and you shouldn’t try to fit them the same way. Remember that the foam used for padding inside the boot will compress with use, so what seems like a very snug fit in a new boot will become more relaxed after just a few days of skiing.
Here are some things you’ll want to consider when choosing a boot:
Start by thinking about where you fit into this Skier Type chart. This will give you an idea of what type of fit, flex and features to look for in a ski boot.
We’ve broken skier types into three groups based roughly on ability:
||Beginner – Intermediate
||Intermediate - Advanced
||Advanced - Expert
||Medium – Fast
||Groomers / Park and Pipe
||Groomers / All Mountain / Park and Pipe / Off-Piste
||Off-Piste / Steeps / Cliffs
Shop Men's Beginner/Intermediate Alpine Ski Boots
Shop Women's Beginner/Intermediate Alpine Ski Boots
You prefer green and blue runs and typically like cruising on groomed terrain. You’re still working on mastering the mechanics of the sport, but are making regular progress. The best option for beginner/intermediates is a softer to medium flexing boot and a fit that will allow them to be comfortable all day long. (Note: An athletic skier who spends many days on snow can easily progress beyond this category in a season or less.)
Shop Men's Intermediate/Advanced Alpine Ski Boots
Shop Women's Intermediate/Advanced Alpine Ski Boots
You enjoy a variety of speeds and conditions, including moguls and steeper terrain, and require more precise steering and control from your boots. You ski blue and some black diamond runs, cruise groomers with confidence and experiment with off-trail terrain. Intermediate/advanced skiers often have several years invested in the sport and should look for a medium flexing boot with a fit that’s precise enough to allow full control in a variety of conditions.
Shop Men's Advanced/Expert Alpine Ski Boots
Shop Women's Advanced/Expert Alpine Ski Boots
Ski boots are measured on a scale called Mondopoint. Mondo (meaning world, but in this case it’s just the skiing world) sizing is the length of your foot measured in centimeters. You can determine your Mondopoint size by tracing your foot on a piece of paper or cardboard with a pen, keeping the pen vertical against your foot so there is just a slight border. Measure the traced outline from the heel to the longest part of the toes. Round off to the nearest half centimeter. (If you don’t have a metric ruler, you can multiply the length in inches by 2.54 to get the centimeter equivalent.) If the tracing of your foot measures 26 cm (10.23”), then your Mondo size is 26.0.
You ski the entire mountain in all conditions with confidence. You easily make the transition from designated
trails to off-piste in a variety of snow conditions including deep powder, crud, ice and moguls. You should be
looking for a boot with a stiff to very stiff flex and a very precise fit. Expert level skiers sometimes intentionally
downsize both in length and volume, then work with a bootfitter to make the boots comfortable. Note: Expert park
and pipe skiers often prefer a roomier fit and softer flex in their boots compared to "traditional" experts.
When fitting (or skiing) ski boots, we suggest wearing a thin or very thin sock. While a thicker sock may be slightly warmer in some instances, the plastic shell and foam in the liner provide lots of insulation, and extra sock thickness between your foot and the boot shell diminishes control and response. In general, the best skiers wear the thinnest socks for this reason.
Beginner/Intermediate skiers should generally choose a boot close to their indicated Mondopoint length, even if it feels small. Keep in mind that the liner of the boot will compress after you ski in it a few times, and you’ll generate more space fairly quickly.
Intermediate/Advanced skiers should also choose a boot close to their indicated size or slightly shorter, but in a stiffer flex. Pay attention to the width of the boot as well, and choose one that offers a snug fit if possible.
Advanced/Expert skiers often choose a shell size slightly smaller than their indicated size for a super precise and responsive fit, and a stiff or very stiff flex. Downsizing in ski boots may call for a collaboration with a skilled bootfitter to make the boots comfortable enough for skiing.
How to Try On Ski Boots
The Proper Size
Slight pressure on your longest toes when the boot is buckled up is usually an indication that the boot will be the right size after some use. If the boot feels too short, try buckling the top buckles and flexing the boot hard – drive your knee forward with all your weight. This will force your heel back into the heel pocket of the boot and create more space in the front. Check the fit of the liner with it out of the boot shell to see if the source of the pressure is the toe of the liner rather than the hard plastic shell – if so, this can usually be stretched by your shop or bootfitter. Keep in mind that while it’s usually possible to enlarge a boot that’s a little too small, it’s virtually impossible to shrink a boot that's too big.
A common method of measuring the length of the boot interior is called a “shell fit,” and it’s a good way to see if a boot is close to the right size. This requires removing the liner (inner boot) from the shell. Insert your foot into the bare shell and slide your foot forward until your longest toes just touch the end of the shell. Then check the distance between your heel and the rear of the shell – most people do this with their hand or a piece of wood of a known thickness, like a ½” dowel. Bootfitters commonly refer to this measurement in terms of “fingers,” which is pretty imprecise because everyone’s fingers are a different size, but tend to average around 15 millimeters (roughly 0.6”) for men. Using this standard, a “one finger” or “one-and-a-half finger” fit (15-22 mm or 0.6 to 0.9”) is considered a good performance fit. More than two fingers is usually too big, while less than one finger is getting into “race fit” range.
Note: Ski boot manufacturers don’t make boot shells in half sizes, so a 26.0 and 26.5 boot normally use the exact same shell. The difference between these two sizes is the amount of padding in the liner and/or insole thickness. For a shoe size conversion chart, check out our Mondo Point Size & Conversion Chart. If you try on a boot and it feels too small or too big, you’ll have to go up or down a full shell size which will be a centimeter larger or smaller.
The length of your boot isn’t your only fit option. Like feet, every ski boot interior has a unique shape. Most manufacturers of alpine boots now make two or three distinct models or “lasts” to fit various types of feet. Generally, these lasts can be divided into narrow, medium and wide, and are based on the width of the forefoot measured on a slight diagonal across the metatarsal heads.
Narrow Last - Narrow lasted boots normally have a forefoot width of 97 mm to 98 mm, and are quite narrow through the midfoot as well. These boots are best for people with narrow and low volume feet.
Shop Narrow Last Ski Boots
Average Last - Average lasted boots have a forefoot width of around 100 mm (give or take a millimeter). These boots fit average feet well out of the box, and have a more relaxed fit through the midfoot and heel than narrow lasted boots.
Shop Average Last Ski Boots
Wide Last - Wide lasted boots are best suited to skiers with wider and higher volume feet, and typically have a forefoot width of between 102 mm and 106 mm.
Shop Wide Last Ski Boots
If you know what width you normally take in a street shoe, you may be able to pick which of these forefoot models most closely matches your foot. An “A” or “B” width foot, for example, usually works best in a narrow lasted boot, while a “C” or “D” width normally fits an average last of around 100 mm. Skiers with an “E” or wider foot should look for a wider, 102 mm or wider last. As with boot lengths, the forefoot width is not an absolute standard among different boot manufacturers, and each has their own formula for determining other dimensions inside the shell, but this is a good general guideline.
Traditionally, stiffer high performance boots were only available in narrower lasts, and expert skiers who happened to have wider feet were forced to simply endure the pain or work with a bootfitter to modify the boots before they could wear them. Beginner and learning skiers who needed a soft flexing boot often had no choice but to buy a wide “comfort” fit boot even if they had a very narrow and low volume foot. This is slowly changing, but expert skiers with very wide and high volume feet and new skiers with very narrow and low volume feet may still find a limited selection to choose from.
Irregularities in the shape of your foot, such as bunions, bone spurs, abnormally long toes or bony protrusions that are not “average” in size or location can also cause fit problems. These problems are often best handled by having an experienced bootfitter modify the boot to accommodate the problem area rather than buying the next larger size.
Boot manufacturers often build more than one model or flex using each last, so if you can find a boot that fits well but the flex isn’t right for you, look to see if it’s available in a softer or stiffer version.
Volume and Instep Height
Volume usually (but not always) goes hand in hand with forefoot width. Boots with a narrow forefoot generally have less volume through the midfoot and heel as well, and boots with a wide forefoot usually have a roomier fit elsewhere in the boot, too. Boot manufacturers don’t list volume as a number, unfortunately, so the best way to tell if a boot’s volume is right for your foot is to try it on.
Instep height (the bony area on top of and slightly forward of your arch) is another key fit area, which bootmakers and models deal with in different ways. Your foot is quite sensitive to pressure on the instep, so wearing a pair of boots for 10 to 15 minutes will usually tell you if there’s an issue. A boot that’s too tight over your instep can be more challenging to fix than one that is too tight around the perimeter of the foot, so pay attention to this part of your foot when trying boots on.
Flex in ski boots refers to how difficult it is to flex the boot forward. Boot flex ranges from very soft to race stiffness, indicated by a numeric “flex index” that’s usually a number from 50 (soft) to 130 (very stiff). Often this number is written on the outside of the boot cuff. The method of determining flex index is not standardized between boot manufacturers, and one company’s 100 flex boot may not equal another company’s 100 flex boot, so use the numbers as a starting point but don’t get too hung up on them. Also, some companies use a 1-10 scale to for their flex rating, which is why we characterize flex as soft, medium, stiff, or very stiff in addition to giving a number rating. Racers and some expert level skiers prefer boots with flex ratings over 130, and these boots are normally available by special order in very low volume shell fits and forefoot widths from 92 mm to 95 mm.
Men’s Flex Rating
||Beginner – Intermediate
||Intermediate - Advanced
||Advanced - Expert
||Expert - Race
|Flex Rating - Men's
Beginner-Intermediate men’s boots range from about 65 to 80 flex index, with Intermediate-Advanced boots going from about 90 to 100. Advanced-Expert boots normally are in the 110 to 130 range. The stiffest race boots are rated at 140 to 150, which is far beyond what most skiers need or want and usually reserved for elite level competition skiers. Again, since there is no industry standard for measuring flex, it’s best to use flex index only as a general guide to choosing which model you’re interested in or as a way to compare models within a single brand.
Terrain, speed and type of snow play a role in choosing your flex as well. Pro level Freeride and Big Mountain skiers often choose a slightly softer boot than top World Cup racers, and pro park skiers go softer yet. Variable snow and very steep terrain often demand a bit more cuff movement, while a hard and uniformly smooth surface (like a race course) and techniques that demand tip pressure require a stiffer flexing boot. Personal preference and physical makeup are equally important. An athletic beginner may do just fine in a medium to stiff boot, and some expert skiers prefer a moderate flexing boot to a very stiff one.
Your height and weight are also contributing factors in choosing the best flex. Someone who is short and light doesn’t put as much leverage on a ski boot and a very stiff boot will be harder to flex, while someone who is larger may require a stiffer boot, even if they are new to skiing. Keep this in mind if you are smaller or larger than average.
Women's Flex Rating
Since women tend to have less body mass for their height and foot size than men, flex ratings are somewhat lower. For women, Beginner-Intermediate boots hover around a 50 to 60 index, with Intermediate-Advanced boots ranging from about 65 to 80. Advanced-Expert boots range from 85 to 110. As with men’s boots, women racers and experts who prefer boots stiffer than a 110 flex will often have to special order them, and they will come with a very narrow and low volume fit.
||Beginner – Intermediate
||Intermediate - Advanced
||Advanced - Expert
||Expert - Race
|Flex Rating - Women's
Matching the cuff to the size and shape of your calf is an important part of your ski boot fit. The shape and height of both the shell and liner cuff can be a big consideration for women (whose calves are generally lower and proportionately larger than men) or those with very large calves. If the upper buckles on a boot are extremely tight out of the box, most boots have upper buckle ladders that can be moved to several different positions, sometimes with a screwdriver or allen wrench, to give you more adjustment range.
Most manufacturers are now offering women specific boots that are designed to fit larger and lower calves, and many women’s models offer an adjustable cuff that will flare out to give you more fit options.
Forward Lean and Ramp Angle
Alpine ski boots normally have a fixed forward lean of between 12 degrees and 18 degrees from vertical. Most modern boot designs reflect the shift in ski technique toward a more upright style and have less forward lean than boots of a few years ago, but the forward lean that works best for each skier is highly personal, and most boots have some adjustment capability. Often this involves installing or removing a spoiler or shim in back of the calf. Alpine touring boots commonly come with two forward lean options.
Ramp angle, or the angle of the boot board (bottom interior of the boot) relative to the ski, is normally fixed as well, but can sometimes be adjusted by a bootfitter or by installing shims under the bindings. Some skiers are more sensitive to ramp angle than others.
Ski boots offer a number of features to enhance performance, comfort and ease of use. Many of these are aimed at customizing the fit and function of the boot, but they vary from model to model.
The liner is the removable, soft inner boot that protects and insulates the foot from the rigid outer shell. All liners will compress (“pack out”) and form to the skier’s foot with use, and a boot that feels tight the first time you try it on will often be just right after a few full days of skiing. Some boots offer a fully customizable thermo liner that can be heated in a convection oven or with heat stacks and formed to the owner’s foot, retaining the exact shape of the foot when they cool. This fitting process is usually best performed by a qualified ski shop; if you aren’t sure which type of liner you have, ask your shop or bootfitter.
A note on Intuition Liners – Standard in brands such as Full Tilt and many Dalbello and Scarpa models, Intuition is a brand of customizable thermo liners made from EVA foam, and can be added to other brands as an aftermarket option. The heat molding process is normally best performed by a qualified bootfitter or shop.
Heat Moldable Shells
Salomon (Custom Shell) and Atomic (Memory Fit) offer outer shells that can be heated in a convection oven and custom molded to your foot. This process works very well to change the shape of a boot shell that is just a bit too tight. The heat molding process should be performed by a qualified shop.
– This is the velcro strap at the top of the cuff of your ski boot (some boots use a mechanical cinching buckle). When tightened, the power strap increases energy transmission and control. It acts as an additional buckle with a large range of adjustability and aids in reducing the gap between leg and boot. Power strap tightness is a matter of personal preference, so feel free to experiment.
– These features are essential to achieving a precise fit. The micro-adjustment actually shortens or lengthens the buckle and will allow you to fine tune the tension between two settings. Turning the buckle clockwise shortens the buckle and tightens the fit; turning it counter clockwise lengthens the buckle and makes the fit looser.
Moveable Buckle Ladders –
Most adult ski boots have moveable buckle ladders (the piece with the notches that the buckle wire attaches to). These normally can be moved using an allen wrench to allow the user a tighter or looser range of settings. You may need to drill a hole in the plastic buckle strap to move the ladder.
– Many boots offer the skier the ability to adjust the upper cuff angle to match the angle of the leg; this adjustability may be important if your natural alignment causes you to weight either your inside or outside ski edges disproportionately. Cuff alignment is normally done by adjusting the rivets attaching the boot cuff to the shell with an allen wrench.
– This is a removable wedge that sits between the liner and the shell directly behind the calf. It serves two functions: It increases forward lean by a few degrees and fills space in the upper cuff to reduce the gap between your leg and the shell, which can be important for those who prefer more forward lean or skiers with very thin legs. Spoilers may be attached to the cuff with screws or may simply attach to the back of the liner with velcro.
Though some fit adjustments are easy to do at home, customization of the following features may require the expertise of a trained boot fitter. See our Custom Ski Boot Fitting: How to Make Your Boots Fit Better for more on how to customize your boots.
– The footbed lives inside the liner, it’s the platform on which the skier’s foot rests. Most stock footbeds provide little support for the contours of the foot. We suggest an aftermarket footbed. Some footbeds are pre-molded and simply trimmed to the correct length while others are fully custom molded specifically to your feet. Footbeds can greatly reduce many fit problems.
– Canting refers to adjusting alignment of the boot to correct a knocked-kneed or bowlegged stance through sole planing, cantable soles or wedges under the binding. Proper canting requires an accurate stance assessment and specialized tools, and not all shops or bootfitters are equipped to do it.
Some ski boot features are aimed at certain types of skiing, like alpine touring or park skiing.
– Many ski boots come with the ability to switch from a fixed ski mode to a walk mode with greater range of motion. This feature is increasingly popular on “crossover” boots that are intended for use both in the ski area and for alpine touring.
– Grippy rubber soles aid in the ability to walk and hike on rocks, ice, and pavement. Many alpine touring boots have a rockered (curved) sole in front of the forefoot for a more natural walking movement. Freeride boots with a grippy sole offer traction for added security while booting and scrambling on rock. Not all traction soles will work with all bindings, so ask your shop if you are unsure about compatibility.
– Some boots offer the user the option of swapping soles, usually from an alpine sole to an alpine touring sole or the reverse. Changing soles may limit your choice of binding, so ask your shop about compatibility if you have any doubts.
Adjustable Flex – Some boots allow you to adjust the forward flex of your boots with cuff hardware. Some also allow you to swap tongues of varying stiffness to fine tune the flex to your liking or to suit conditions.
– Bootboards (also called "Zeppas") are the removable platforms that the liner sits on top of in the shell. Rigid bootboards provide the most efficient transfer of energy to your skis. Some bootboards are made out of rubber or have padding to soften harsh landings. These are typically seen in park and pipe boots and big mountain boots.
Shock Absorbers – There are other padded features often seen on park-specific boots. Look for padded spoilers, tongues, heels, and toes. All of these help in reducing shock commonly referred to as toe, shin, and calf-bang.
Purchasing Ski Boots on the Internet
Now that you know what you need from your boots and have the tools to begin your search, we strongly recommend you resist the urge to buy strictly on price or color. It’s wise to save elsewhere in your budget if it means getting the right boot.
No one knows how your feet feel better than you. If you think you’ve got a boot that comes close to the fit and flex you want, try wearing them at home for several hours before you head to the mountain with them. Put the boots on, buckle them as you would to ski, and stand up to watch a movie or a game. You’re going to have to be able to wear these things for at least that long if you’re going to ski in them, right? If they still feel pretty good after two hours or so, you may be ready to go. If you have localized pain at a toe or bony area, a bootfitter may be able to fix the problem. If you have serious fit issues with the boot, you’ll probably know it well before the two hours are up.
Your overall skiing experience depends on getting the fit and features that best suit your foot and skiing style, so take your time and feel free to call us for help at 1.866.386.1590.
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Learn more with our other Ski Guides:
Skis – How to Choose & Size Chart
Skis – Kids' Size Chart
Skis – Rocker Technology
Alpine Touring Skis – How to Choose
Skis – Weight Chart
Ski Boots – Size Chart
Ski Boots – How to Try On
Ski Boots – How to Make Your Boots Fit Better
Alpine Touring Ski Boots – How to Choose
Ski Boots – Weight Chart
Ski Boots – Boot Sole Length Chart
Ski Bindings – How to Choose & DIN Setting Chart
Alpine Touring Ski Bindings – How to Choose
Ski Bindings – Weight Chart
Ski Poles – Size Chart
Skiing – How to Get in Shape
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Still have questions? Please give our customer care team a call at 866-386-1590, Customer Care Hours. They can help you find the right fit for your needs.