What size ski jacket to buy, and how much room to leave

Ski jackets are already sized for layers

The most common sizing mistake in ski outerwear comes from a reasonable assumption: you will be wearing a lot underneath, so go up a size. It is wrong because the jacket makers already did that. A ski jacket in a given size is cut wider through the chest and longer in the sleeve than a street jacket in the same size, because the pattern assumes a base layer and a mid layer are underneath. Add a size on top of that and you get a garment with a large volume of air in it.

That air is the problem. Warmth comes from still air trapped close to the body. A jacket with too much room lets that air move, and moving air carries heat away. It is the same reason a thick sock makes a ski boot colder, and it is counterintuitive in exactly the same way. An oversized jacket is also the one that rides up when you lift your arms, which drops snow down your back on the first fall.

The four movement checks

Do these wearing what you will actually ski in: a base layer and a mid layer, not a t-shirt. Each one takes seconds and each one catches a different failure.

The hood test is the one people skip and regret. A hood that fits a bare head and not a helmet is useless on the day it matters, because the day you want a hood is a day with wind and snow, and that is also a day you are wearing a helmet. Any jacket sold for skiing should publish a helmet-compatible hood; if it does not say so, assume it is not.

Length is the specification nobody checks

Two lengths matter and they behave differently.

Body length

A ski jacket should cover your waistband when your arms are over your head, which for most people means a hem somewhere around the top of the thigh. Shorter than that and every fall puts snow between the jacket and the pants. This is what a powder skirt exists to fix, and the features page covers whether you need one.

Sleeve length

Sleeves should reach past the wrist bone with your arms forward, because that is where your arms are when you ski, not at your sides. A sleeve that is correct in the shop with your arms hanging down will be two inches short in a pole plant. On a jacket with a gauntlet cuff on the gloves, the sleeve goes over the glove; on a jacket with an inner cuff, the cuff goes under it. Either works, but you have to pick one and buy gloves to match. The glove sizing page covers the cuff question.

Body length and sleeve length are also where brands differ most. Columbia publishes regular, big and tall variants for the Whirlibird V, which is the cleanest solution available at family prices if you are outside the standard pattern. Most brands publish only one length per size.

Pants have one extra variable: inseam

Snow pants get sized on waist and inseam, and the inseam is where family sizing falls apart, because a household of four rarely contains four catalog inseams. It is worth knowing which brands publish more than one option. Arctix publishes its insulated cargo pants in 28, 32 and 34 inch inseams. Columbia publishes an adjustable inner leg length on the Bugaboo IV, which quietly solves the same problem from the other direction.

Snow pants should sit long enough that the cuff covers the top of the boot with a knee bent, and the internal gaiter should sit over the boot rather than inside it. Too short and you get snow in the boot; too long and you stand on the hem with a ski edge, which cuts it. The pants roundup compares the published specifications.

Women, children, and the sizes brands do not publish

Women’s ski outerwear is usually cut with a different shoulder-to-hip ratio rather than simply scaled down, so a men’s jacket in a smaller size fits differently rather than fitting smaller. If a brand publishes both, take the one cut for your shape; if it publishes only one, run the four movement checks and judge on those.

Children are the opposite problem: they are between sizes constantly, and the temptation is to buy two sizes up so it lasts. A jacket two sizes up has sleeves that swallow the hands and a hem that catches under a chairlift. The growing-room page draws the line at where extra room is fine, and outerwear is the one category where a single size of growing room genuinely works, especially in a jacket with roll-back cuffs. The kids jacket roundup lists what publishes what.

Buying without a fitting room

• Measure your chest and your sleeve, and use the brand chart. Not the generic one. Sizing runs differently at every brand and the maker chart is the only one that describes the garment you are buying.
• Order one size, not two. The two-size return strategy sounds sensible and mostly results in keeping whichever arrived first.
• Try it on over your real layers, indoors, immediately. Run the four checks. A jacket that binds in your living room binds harder in the cold.
• Keep the tags on until you have done the hood-over-helmet test. It is the check that most often sends a jacket back.
• Check the return window against your trip date. Buying in November for a February trip is how people discover a bad fit two months after the window closed.

If the whole question is making you wonder whether to buy at all, the rent-or-buy page on clothing is worth reading first. Outerwear is the category where the arithmetic is least obvious, because a ski jacket also works as a winter coat for the other fifty-one weeks.