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I currently use La Sportiva WildCat Trail Running Shoes size 43 for trail running/light hiking and Nepal EVO's size 44 for Ice Climbing and Alpine adventures. The Nepal EVO's fit me perfectly with a good midweight sock and using their additional tongue for the left foot which is slightly smaller than my right.

I am looking at purchasing La Sportiva Olympus Mons EVO's for high altitude such as Denali and other real cold expedition type adventures that require a double boot.

My question is how much larger do I size them to accommodate for the swelling of the feet at high altitude? Would one full size be ok? I am thinking a half size for thicker sock+ sock liner and a half size for the swelling of the foot, is this accurate or should I be sizing up even larger?

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My experience with double plastic boots has been that it's basically just impossible to get ones that I can use. Every size I've tried is either too small in one area or too big in another. If you get them too big, they rub and give you blisters. As you get into heavier and heavier footwear, it gets harder and harder to make it work without causing foot problems. I'll be interested in seeing the answers to this question. Maybe there are ways to customize the boot, such as filling in some spaces with shims...? Don't buy a pair that you can't test and then immediately return if necessary. – Ben Crowell Mar 15 '14 at 20:11
An option to consider before Denali would be to do a lesser climb in an area where it's possible to rent double plastic boots. E.g., I know you can rent them in Shasta, and I think you can rent them in the alps in towns like Chamonix. This gives you a chance to find your size without throwing away money. Double plastic boots aren't at all necessary for Shasta, but they'll work, and you can test them in realistic conditions over a couple of days. REI is also extremely permissive about returns. – Ben Crowell Mar 15 '14 at 20:16

1 Answer 1

up vote 4 down vote accepted

British mountaineer Andy Kirkpatrick has quite a bit of useful information regarding how to look after your feet at altitude and in cold conditions on his website at

The only recommendation on footwear size he gives with respect to high altitude, is for Neoprene socks. He recommends allowing room for feet swelling and expansion of bubbles in the neoprene by probably going up one size than usual for the neoprene socks.

Another website, , only mentions ensuring the boots fit you properly but don't mention leaving room for swollen feet due to the altitude.

From these suggestions it would appear that as long as the boots fit properly when you try them on, there should be no need to leave extra room for swollen feet.

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Thx for the answer and the links! I am asking myself exactly that question right now. I am fine while walking around in the city at low altitude but have no clue how much the foot swelling due to high altitude (>20k feet) will be... – Wills Mar 17 at 20:42
And another problem is to detect how much room you have in those ultra stiff boots. You can't do the feel-the-wiggling-toe-test through the shoe like you do for street shoes. What you notice is (when e.g. buying one or even two sizes bigger) if you are getting heel lift or in general the foot is moving too much in the boot. I don't like to gamble that my swollen foot will fill that space when I am at high altitude. And I want to use that boot for lower altitudes too. – Wills Mar 17 at 21:35

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