Base1 Just Flow - Under ArmourⓇ athletic t-shirt

Base1 Active Size Guide

All measurements are approximate. For the best fit, measure yourself and compare to the charts below. If you're between sizes, size up for a relaxed fit or size down for a tighter, athletic fit.

How to Measure

• Chest: Measure around the fullest part of your chest, keeping the tape level.
• Waist: Measure around your natural waistline, just above your hip bones.
• Hips: Measure around the fullest part of your hips.
• Length: Measure from the highest point of the shoulder to the hem.

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Hoodies & Sweatshirts (Unisex / Oversized)

Our hoodies run oversized. Order your usual size for the intended relaxed fit.

Size	Chest (cm)	Length (cm)	Sleeve (cm)
XS	53	66	61
S	55	69	63
M	58	72	65
L	61	74	67
XL	64	76	69
2XL	67	78	71
3XL	70	80	72

T-Shirts (Unisex / Oversized)

Our oversized tees have a drop-shoulder, relaxed fit. Order your normal size.

Size	Chest (cm)	Length (cm)	Sleeve (cm)
S	53	72	23
M	56	74	24
L	59	76	25
XL	62	78	26
2XL	65	80	27
3XL	68	82	28
4XL	71	84	29

T-Shirts (Classic / Regular Fit)

Size	Chest (cm)	Length (cm)
XS	46	66
S	48	69
M	51	72
L	53	74
XL	56	76
2XL	59	78

Joggers & Sweatpants

Size	Waist (cm)	Hip (cm)	Inseam (cm)
S	74	96	74
M	79	101	76
L	84	106	78
XL	89	111	79
2XL	94	116	80

Shorts

Size	Waist (cm)	Hip (cm)	Length (cm)
S	74	96	47
M	79	101	48
L	84	106	49
XL	89	111	50
2XL	94	116	51

Leggings & Sports Bras (Women's)

Performance fit — stretchy fabric, order your usual size.

Size	Waist (cm)	Hip (cm)	Inseam (cm)
XS	60	83	69
S	64	88	70
M	68	93	71
L	74	99	72
XL	80	105	73

Swim Trunks

Size	Waist (cm)	Hip (cm)	Outseam (cm)
2XS	72	90	41
XS	76	94	42
S	80	98	43
M	84	102	44
L	90	108	46
XL	96	114	48
2XL	102	120	50

Basketball Jerseys & Tanks

Size	Chest (cm)	Waist (cm)	Hip (cm)
2XS	88	72	90
XS	92	76	94
S	96	80	98
M	100	84	102
L	108	92	110
XL	116	100	118
2XL	124	108	126
3XL	132	116	134

Hats & Beanies

One size fits most. Snapbacks have an adjustable closure. Beanies are stretchy acrylic — one size fits all.

Style	Circumference (cm)
Snapback Cap	54-60 (adjustable)
Cuffed Beanie	48-58 (stretch fit)

Kids

Age	Size	Chest (cm)	Length (cm)
3-4	3/4Y	56	42
5-6	5/6Y	60	46
7-8	7/8Y	64	50
9-11	9/11Y	70	55
12-14	12/14Y	78	62

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Still unsure? Email us at matt@baseone.uk with your height, weight, and usual size, and we'll recommend the best fit for you.

Made to order — please allow 3-7 business days for production before shipping.

UK delivery: 2-5 business days from dispatch (from £1.85)

International: 5-20 business days depending on location

Returns: 30 days for faulty or damaged items. See our Returns Policy for full details.

Free shipping on orders over £75 with code FREESHIP75.

We use premium, responsibly sourced materials across our range:

• Organic cotton — GOTS certified, grown without pesticides
• Recycled polyester — made from post-consumer plastic bottles
• Performance blends — moisture-wicking and quick-dry fabrics

Every Base1 product is made on demand — zero overproduction, zero waste. Better for you, better for the planet.