How To Choose Ski Boots

Ski boots are undoubtedly the most important piece of equipment a skier owns. That said, finding the right boot comes down to a number of personal factors, including foot shape, weight, and skill level. Our How to Choose Ski Boots Guide details how to best approach the boot buying process and what to look for when sifting through all the different types of ski boots.

What Type of Ski Boot Is Right for Me?

Choosing the right ski boot comes down to a number of very personal variables including your skiing style, skill level, foot size and shape, weight, and a number of other factors only a skilled boot fitter will be able to determine. Because of that, choosing a ski boot should be a hands-on process with a professional boot fitter. Working directly with a professional is the best way to guarantee you’re getting the right size and model for your needs.

So when it comes to how to choose ski boots online, the answer from our perspective is, well, don’t. We recommendworking with your local ski shop to find, fit, and purchase your ski boots. With that being said, you can educate yourself on a few things that will help you better understand the process.

Types of Ski Boots

As skiers, we’re certainly spoiled for choice in the amount of different boots available today. As you navigate all the different types of ski boots, last widths, flexes, and even sole types, a professional boot fitter will be able to steer you towards the right boot for your skiing style and, perhaps most importantly, foot shape and size.

As a jumping off point, it’s important to know that ski boots are categorized in terms of flex (or stiffness), last width, shell design, and even sole type. It’s also important to note that while a particular ski boot may match the intended use and shell design you’re looking for, it may not be the right boot for your foot.

Alpine / Resort

Standard alpine ski boots designed for resort skiing feature the most diverse offering of styles. From borderline race boots to touring-capable models, a wide range of options are available to suit an array of skiing styles. These boots are available with Alpine, WTR, or GripWalk soles. They are also available in either a two-piece or three-piece Cabrio shell design and may include some form of walk mode.

Race / Plug

Since each manufacturer makes only a few select models of true race boots, they need to be able to be shaped to a wide range of foot/ankle structures. This means the template is as undefined as possible, and it requires extensive boot work to get them into skiing condition. The benefit of this is a fully optimized fit that maximizes energy transfer from skier to skis.

Touring / Backcountry

Touring ski boots are designed for backcountry travel. They always feature some form of walk mode setting for enhanced range of motion for skinning or hiking, which can be locked out when it’s time to ski downhill. These boots are designed for use with either frame or tech bindings (sometimes both) and minimize weight to varying degrees for uphill efficiency.

Shell Design

Overlap / 2-piece

Overlap ski boots utilize a two-piece construction, consisting of a solid upper cuff attached to the lower shell via the spine. Overlap boots generate their stiffness and rebound from the spine (or rear) of the boot.

Cabrio / 3-piece

Cabrio ski boots utilize a three-piece construction, consisting of a lower shell, upper cuff, and tongue. Cabrio boots generate their stiffness and rebound from the tongue (or front) of the boot.

Comparison of an overlap ski boot. Image courtesy of Dalbello.
Comparison of a Cabrio ski boot. Image courtesy of Dalbello.

Ski-Hike / Walk Modes

Hike/walk modes utilize a lock-out lever on the spine of the boot that allows for adjustments to the stiffness, range of motion, and rebound (i.e. it optimizes the flex for either walking or skiing). Some mechanisms aim for only a slight softening to take the pain out of hiking, while others fully disengage the upper cuff for near-effortless walking.

Types of Ski Boot Soles

Alpine (ISO 5355)

ISO 5355 refers to ski boots with traditional alpine soles. ISO 5355 is further categorized by Adult Alpine (Type A) and Junior or Children Alpine (Type C).

Alpine (ISO 5355) boot sole. Image courtesy of Fischer.

Touring (ISO 9523)

ISO 9523 refers to most ski boots with touring soles. These soles typically feature a rockered profile and rubber compound along the sole designed to make walking easier.

Touring (ISO 9523) ski boot sole. Image courtesy of Fischer.


GripWalk is a sole-binding system from Marker. In terms of your boots, GripWalk takes the form of co-polymer soles with a rocker profile designed to enhance walking comfort. GripWalk-compatible bindings are specifically designed for these soles and require no toe-height adjustment for either GripWalk or ISO 5355 Alpine soles.

GripWalk ski boot sole. Image courtesy of Fischer.

Ski Boot and Binding Compatibility

We should preface this section by saying that a truly complete breakdown of boot-to-binding compatibility would need to be specific by brand, model, and year, while also accounting for all models and years from each brand, and any possible inter-brand combination. That level of detail is best left to manufacturer compatibility charts, of which there are many.

There are some key things to keep in mind when considering whether a pair of ski boots will be compatible with your existing bindings. Below you’ll find some high-level binding requirements for ski boot soles.

Binding Requirements:

Alpine (ISO 5355)

Boots with alpine soles are compatible with Alpine (ISO 9462) ski bindings.


Boots with GripWalk soles are compatible with GripWalk bindings and most Alpine (ISO 9462) ski bindings with adjustable toe height.

Touring (ISO 9523)

Boots with Touring soles are only compatible with Multi-Norm Certified (MNC) ski bindings with Tech inserts.

Tech Toe

Boots with Tech toe inserts are compatible with Tech bindings for engagement via metal pins. Some tech-compatible boots are also equipped with soles compatible with Alpine (ISO 5355), WTR, GripWalk, and/or MNC soles.

Adjustable Toe Height

Another point to emphasise when discussing binding requirements for a given ski boot is whether or not the binding features an adjustable toe height. This feature allows for the boot-sole interface in the binding’s toe piece to move up and down, ensuring that the boot properly seats and interfaces with the binding. This is important when considering whether a boot with WTR or GripWalk soles will be compatible with an Alpine (ISO 9462) ski binding.

For even more information on boot-binding compatibility, check out our How to Choose Alpine Ski Bindings Page.

Flex Index

The first thing to know about flex indexes is that no industry standard exists. But there are several factors you can use to help you understand how it’s measured, why it matters, and how to match it to your skill level and weight.

How is Flex Measured?

Because different manufacturers measure flexes differently, flex indexes function more as guidelines. It would be nice if a flex index of 100 was the same for every manufacturer, but they aren’t. They are, however, relevant for comparisons between manufacturers, but there is no consensus for determining flex. For example, the 120 flex of your old Atomic boots may not feel anything like the flex pattern of a new pair of 120 flex Tecnicas.

So Why Does Flex Matter?

To understand the importance of flex, you need to think of it in terms of both its out (resistance) and back (return) path. In that sense, flex index is referencing a ski boot’s ability to resist forward driving forces, convert that resistance into loaded energy, and then fire it back in order to return to its starting point. This resistance, load, and return is how you generate the energy and power necessary to flex your skis and carve turns. Too much resistance, and you’ll never be able to properly load the boot and generate power; too little and the boot will never load enough energy to return you to your neutral stance. By properly matching flex to your skill level, weight, body geometry, and usage, you are able to ensure that your ski boots complement your skiing style.

Skill Level and Flex

Skill level can influence the proper flex of your ski boots. Beginners generate less force on their boots and are more focused on staying upright and easing onto their edges, so a softer flex ensures more forgiving articulation, fore/aft movement, and compliance to initiate turns. Advanced skiers, meanwhile, drive into their turns with aggression, which requires a stiffer flex index that can handle the powerful forward flex while still being able to rebound back into place.

Matching Flex to Weight

Body weight is another determining factor for selecting the appropriate ski boot flex, but only insofar as its ability to meet the minimum requirements of resistance and rebound. That is to say, body weight is more of an influence on whether a boot is too soft than too stiff.

For example, a 230-pound beginner skier will not get the resistance and rebound they need from an 80-flex ski boot. They simply outweigh the flex index. On the other hand, a 130-pound expert skier with impeccable form, balance, and positioning might very well be able to crush a 130-flex ski boot.

Bootfitters Can Match Flex

It’s important to note that neither skill level nor weight can be treated as standalone determinators of proper flex index. Not only do those two factors intertwine, but they don’t even account for the full list of influences: tibia length, natural stance and posture, the path the knee travels, room temperature, etc. For a deep dive on flex index, check out our blog, Ski Boot Flex Explained, by Jans Ambassador, Jackson Hogen, of

Getting your boots fitted by a bootfitter is crucial to your comfort and performance on the mountain. Image courtesy of Atomic.

Last Width and Volume

While last width is used interchangeably with volume these days, they are actually two different components of how a ski boot fits.

Last Width

Last width refers to the width (in millimeters) of the forefoot and is based on average measurements of a slight diagonal across the metatarsals. Basically, the widest point of your foot dictates the last. In terms of the last width listed for a ski boot by the manufacturer, this measurement is based on the width at Mondo size 26.5 (for men) and 24.5 (for women), with the width increasing or decreasing with each size up or down. In other words, the listed last width of a ski boot is simply a starting reference point.

Last width is an especially important consideration when it comes to determining if a ski boot will be too wide for your foot shape. Last width can be manipulated to accommodate wider feet through punching, stretching, or grinding the shell or liner, but it can’t be shrunk. So when choosing a ski boot, it’s helpful to know the last width of your foot and stick with models that fall at or below that threshold.

Last width is the width of the forefoot and is best measured by a bootfitter. Image courtesy of Atomic.

Here are some rough guidelines for understanding last in terms comparative width:

98mm (and below)

98mm is a fairly standard last width for performance-focused ski boots and is considered narrow. Race boots can go as low as 92mm.


99-102mm lasts are considered to be of medium width. This last width is found on everything from performance alpine boots to freestyle boots. Ski touring boots usually use a last within these widths (or wider) to keep feet comfortable while consistently expanding/contracting while walking or skinning.

102mm (and higher)

102-106mm lasts are considered wide and are most commonly found in purpose-built boots designed specifically for people who are extremely wide across the forefoot.


The volume of a ski boot refers in general terms to the overall space within the shell. Choosing a boot with the right volume for your body geometry requires an understanding of the height of your instep, shape of your Achilles, general ankle structure, calf configuration, etc. In other words, it’s something best left to the determination of a trained bootfitter.

Mondopoint Sizing

Ski boot sizes are listed in Mondopoint, which is basically your shoe size in centimeters. By using Mondopoint sizing, a ski boot made in France will reference the same listed sizes as a boot made in the USA. Mondopoint sizing can be especially cumbersome for non-Metric skiers, so here’s a helpful chart to zero-in on your Mondopoint size:

Mondopoint size chart. Image courtesy of Atomic.

We strongly urge you to use the above chart solely for approximation. The only foolproof way to ensure you’re getting the proper size ski boot is to get measured by a trained bootfitter and personally try on a given boot. Not all 27.5 boots feel the same in terms of length, and some manufacturers are notoriously short or long with their sizing.