Thermals & Base Layers

Thermal underwear and base layers for men, women and children, from Heatwave Thermalwear and Daisy Dreamer. The collection includes long johns, long janes, thermal T-shirts and long sleeve tops, matching top and bottom sets, and 140 denier thermal leggings and tights, made to be worn under workwear, school uniform, outdoor gear or everyday clothes.

How a base layer works

A base layer is the layer that sits against your skin. It holds a thin layer of warm air next to your body, and a brushed inner face, like the one on the Heatwave long johns and thermal T-shirts, helps it do that. You then add a mid layer, such as a jumper or fleece, and an outer layer, such as a coat. Several thin layers trap more warm air than one thick one, and you can take one off when you go indoors.

Some of the Heatwave thermals list a tog rating of 0.45. Tog measures how well a fabric holds in heat: the higher the number, the warmer it is. Moisture matters too, because damp fabric feels cold, so several styles here are described as breathable or moisture-wicking.

Getting the fit right

Base layers work when they sit close to the body, snug but not tight, because gaps let warm air escape. Most tops and bottoms here use a ribbed knit that shapes to the body, and the men's long johns are close-fitting by design so they layer under work trousers or jeans without bunching behind the knee.

The men's styles run S to XXL. The men's long johns list approximate waist sizes: Small 29 to 32 inches, Medium 33 to 35 inches, Large 36 to 38 inches, XL 39 to 42 inches and XXL 43 to 45 inches. Women's and children's sizes are on each product page.

Fibres and what they do

50% polyester, 50% cotton: used in the Heatwave men's tops, long johns and boys' thermals. The cotton keeps them soft, and the long johns are described as holding their shape through repeated washing.
Cotton-rich blends: the Daisy Dreamer women's and girls' thermals, described as breathable with a ribbed, body-hugging fit.
Polyester and elastane: the 140 denier thermal leggings (95% polyester, 5% elastane, brushed) and thermal tights (90% polyester, 10% elastane). Elastane gives stretch, and 140 denier is a thick weight for cold days.

Look out for side seam-free tops in one of the men's sets, which means fewer seams against the skin under a work shirt.

Thermals for children

The girls' set pairs a long sleeve top with long janes in a cotton-rich blend and is described for wearing under school uniform or ski gear. The boys' set is a long sleeve top and pants in charcoal black, and the boys' long johns come in a pack of two for school, camping and skiing. Choose a snug size rather than one to grow into, as a loose base layer holds less warmth.

Common questions

Should thermal underwear be tight or loose?

Snug but comfortable. It should sit against the skin without gaps, but not dig in at the waist or cuffs.

What does 0.45 tog mean on thermals?

Tog is a measure of how well a fabric holds in heat. A higher number is warmer, and 0.45 is the rating listed on several Heatwave tops and long johns.