Heatwave Thermalwear Boys Winter Thermal Long Sleeve Top And Pants Set Charcoal Black Brushed Base Layer Warmth

£12.00

In stock

Colour

Size

Size Guide

All sizes are UK sizes. Measure over underwear with a soft tape and compare with the charts below. If you are between sizes, choose the larger size for nightwear, loungewear and dressing gowns.

Each brand fits slightly differently. Where a product description gives the brand's own size chart, follow that one. Not sure? Email hello@cosycart.co.uk and we'll help, and remember you have easy 14-day returns.

Jump to: Women · Men · Teenagers · Kids · Baby · Slippers and socks

Women

UK size	Bust (cm)	Waist (cm)	Hips (cm)	Letter
6	78-81	60-63	86-89	XS
8	82-85	64-67	90-93	S
10	86-89	68-71	94-97	S
12	90-94	72-76	98-102	M
14	95-99	77-81	103-107	L
16	100-104	82-86	108-112	L
18	105-110	87-92	113-118	XL
20	111-116	93-98	119-124	XXL
22	117-122	99-104	125-130	XXL

Men

Size	Chest (cm)	Waist (cm)	Chest (in)	Waist (in)
S	86-94	71-79	34-37	28-31
M	95-102	80-87	38-40	32-34
L	103-110	88-95	41-43	35-37
XL	111-118	96-103	44-46	38-40
XXL	119-126	104-111	47-49	41-43
3XL	127-134	112-119	50-52	44-46

Teenagers

Age	Height (cm)	Chest (cm)	Waist (cm)
11-12	146-152	74-77	62-64
12-13	152-158	77-80	63-66
13-14	158-164	80-84	65-68
14-15	164-170	84-88	67-70
15-16	170-176	88-92	69-72

Kids

Age	Height (cm)	Chest (cm)	Waist (cm)
2-3	92-98	53-55	51-52
3-4	98-104	55-57	52-53
4-5	104-110	57-59	53-54
5-6	110-116	59-61	54-55
7-8	122-128	63-66	56-58
9-10	134-140	68-71	59-61
11-12	146-152	74-77	62-64

Baby

Size	Height (cm)	Weight (kg)
Newborn	up to 56	up to 4.5
0-3 months	56-62	4.5-6
3-6 months	62-68	6-7.5
6-9 months	68-74	7.5-9
9-12 months	74-80	9-10
12-18 months	80-86	10-11.5
18-24 months	86-92	11.5-13

Slippers and socks

UK shoe size	EU	Usual sock size
3-4	36-37	Women UK 4-8
5-6	38-39	Women UK 4-8
7-8	40-42	Men UK 6-11 / Women UK 4-8
9-10	43-44	Men UK 6-11
11-12	45-46	Men UK 11-13

How to measure

Bust / chest: around the fullest part, keeping the tape level under the arms.
Waist: around your natural waistline, the narrowest part.
Hips: around the fullest part of the hips.
Children and babies: height is the most reliable guide; size up if they are growing quickly.

🚚 Order today: usually with you in 3-5 working days, tracked from UK stock

When the cold bites, you need a base layer that works as hard as you do — genuinely warm, genuinely comfortable, and invisible under everything you wear.

Key Features

Advanced Insulating Yarn — The thermal underwear base layers are crafted from an advanced insulating yarn.
Comfort Fit Design — The ribbed construction of the set shapes to the contours of the body, offering a perfect fit.
High Performance Insulation — The combination of 50% polyester and 50% cotton provides excellent insulation while maintaining breathability.

Materials

The combination of 50% polyester and 50% cotton provides excellent insulation while maintaining breathability. The materials are specifically designed to keep children warm without overheating.

Colours Available

Black, Charcoal

Sizes Available

Ages 3-5: Long Sleeve Top Chest to Fit Approx 20-22", Long John Pants Waist to Fit Approx 20.5" Ages 6-8: Long Sleeve Top Chest to Fit Approx 24-26", Long John Pants Waist to Fit Approx 21.5" Ages 9-11: Long Sleeve Top Chest to Fit Approx 28-30", Long John Pants Waist to Fit Approx 22.5"

Care Instructions

Machine washable at 40°C Can be tumble dried Wash dark colours separately.

Perfect For

Perfect Christmas gift for outdoor enthusiasts, hikers, and skiers A thoughtful birthday treat for them who feels the cold Great Secret Santa present — practical, comfortable, always appreciated Ideal self-care gift for anyone who spends time outdoors in winter.

Frequently Asked Questions

Is this warm enough for skiing or outdoor sports?
Yes — the insulating yarn and brushed interior are engineered for cold-weather performance as a base layer for skiing, snowboarding, and hiking.

Can I wear this under everyday clothes?
Absolutely. The slim ribbed fit layers smoothly under jeans, trousers, or work attire without adding visible bulk.

Is it suitable for sensitive skin?
Yes — the hypoallergenic fibres are gentle and non-irritating for comfortable all-day wear.

What sizes are available?
Please refer to the Sizes Available section for the full range. If you're between sizes, we recommend sizing up for the most comfortable layering fit.

Is it machine washable?
Yes — machine wash at 40°C. Easy to care for, wash after wash.

Free tracked UK delivery over £15

Free tracked delivery on UK orders over £15 (£2.99 below that). Everything is sent from UK stock and most orders arrive in 3-5 working days.

Easy 14-day returns

Changed your mind? Tell us within 14 days of delivery and return unused items for a refund of the item price (return postage paid by you).

Secure checkout

Pay safely with card, Apple Pay, Google Pay or Shop Pay. Questions? Contact us any time.