Fit & sizing
How Much Room to Leave for Layering
The right amount of room is enough for the thickest layer you'll actually wear, and no more. That sounds obvious, but most layering mistakes come from imagining a winter that Ireland rarely delivers, or forgetting the jumper you wear every day from October to March.
Start with what you'll wear underneath
Ireland's weather is mild, damp and changeable. It rarely gets very cold, and winter days are often 4 to 8°C and wet rather than freezing. So most people don't need room for a stack of heavy layers. What they need is room for one good mid layer, a fleece or jumper, under a jacket that keeps the wind and rain out.
| Season | What you'll usually wear underneath | What it means for fit |
|---|---|---|
| Summer | T-shirt or shirt | A light shell can fit fairly close |
| Spring and autumn | Light jumper or thin fleece | Room for one light layer |
| Winter | Jumper, fleece or light insulated jacket | Room for one thicker layer |
Then ask what job this particular jacket does:
- A rain shell you'll wear all year needs room for a fleece in winter.
- A puffer or insulated jacket is the warm layer itself, so it usually fits closer.
- A winter parka or overcoat needs room for a jumper, but rarely more.
- A blazer goes over a shirt or fine knit, never a chunky jumper.
The practical approach
- Pick your thickest real layer. Be honest. The jumper you wear on the school run every week in January should decide this, not the chunky knit you wear twice a year.
- Wear it when you try the jacket on. If you're shopping in person, bring it. If you're buying online, try the jacket at home over that layer before you remove the tags.
- Zip it fully and move. Hug yourself, reach forward as if to handlebars, and lift both arms overhead.
- Check the sleeves. The jacket sleeve should slide over your jumper sleeve without dragging it up to your elbow.
- Then try it with just a T-shirt. If it swamps you, look for a different cut in your size rather than a smaller size. Our guide to slim, regular and relaxed fit explains the difference.
Signs there isn't enough room
- You have to breathe in to close the zip, or it strains once closed
- Your jumper sleeves bunch up at the elbows
- The back pulls tight when you reach forward
- The armholes cut into your armpits
- On a puffer, the fill looks flattened across the chest and shoulders
That last one matters. Insulation, whether down or synthetic, keeps you warm by trapping air. Squash it and it traps less, so a tight puffer is a colder puffer. More on how fill behaves in down vs synthetic jackets.
Why too much room is a problem too
It's tempting to size up "just in case". The trouble is that a jacket keeps you warm by holding a layer of still, warm air around your body. When there's a big gap, every movement pumps that warm air out at the hem and collar and pulls cold air in. Outdoor clothing designers call this the bellows effect.
Extra room also lets the wind in. On an exposed day in Connemara or Kerry, a baggy jacket flaps and fills like a sail. On a waterproof, loose cuffs, hems and collars give the rain more ways in, which is why hem drawcords and cuff tabs are worth using.
There's a practical cost too. Sizing up to make room for layers usually makes the sleeves longer and the shoulders wider, so the whole jacket fits worse. If you need more room through the body, a relaxed cut in your normal size often fits better than a slim cut one size up.
Shells vs insulated jackets
Waterproof shells
A shell is the outer layer of a system. It should fit over a base layer and a fleece, or a thin insulated jacket, without pulling. Many outdoor shells are cut with this in mind, so if the brand describes a jacket as having room for layers, believe it and don't size up again. Browse waterproof jackets with that in mind.
Puffers and insulated jackets
These have the warmth built in, so they're usually worn over a T-shirt, base layer or light jumper and can fit closer. If you plan to wear a thin puffer as a mid layer under a shell, try the two together: the puffer must fit inside the shell without squashing. See our puffer jackets section for the different weights.
Fleeces and softshells
Fleeces are usually a mid layer, so they fit fairly close to the body over a base layer. Softshells sit somewhere between: close enough to move well, roomy enough for a light layer underneath.
Winter coats and parkas
A winter jacket or parka usually needs room for a jumper, because many people wear it over work clothes on a cold commute. Check that it still closes comfortably over that jumper when you sit down on the bus or in the car.
