Motorcycle gloves are sized by hand circumference across the palm at the knuckles, thumb out. Alpinestars’ men’s chart runs S 17.8–20.3 cm, M 20.3–21.6 cm, L 21.6–22.9 cm, XL 22.9–24.1 cm, 2XL 24.1–25.4 cm, 3XL 25.4–27.9 cm; European makers also label by the EN ISO 21420 number, size 9 being a 229 mm (9") hand.
Race, sport and touring cuts
Race gloves with hard knuckle armour (tested to EN 13594) are cut close so the armour sits on the knuckles and the fingers do not roll in a slide; touring and winter gloves are cut looser for a liner and warmth. When the hand sits on a band edge, a race glove usually goes to the smaller size and a winter glove to the larger.
A 21 cm hand is an Alpinestars M; XL at 22.9 cm.
measure round the palm at the knuckles, thumb out EN size = circumference in inches
Riding hand
Measure the hand you grip with most, usually the throttle hand, and the larger of the two if they differ.
Brand cuts differ inside a size: when the sizer lands between two sizes, or on the edge of a band, try both.
Women’s, youth and winter riding gloves
Women’s motorcycle gloves are cut narrower in the palm and shorter in the fingers for the same circumference; most makers label them one letter smaller than a man’s glove for the same hand, as work and dress gloves do (a 178 mm hand is a unisex S and a women’s M).
Winter and heated riding gloves add insulation and a membrane inside: size them like ski gloves, over any liner, and expect the fingertips to need a little more room. Measure the hand that grips the throttle, and if your hands differ, buy for the larger.
Gauntlet gloves also need to close over the jacket cuff: check the cuff circumference on the maker’s page as well as the hand size.
Why the screen can be trusted
A browser does not know how big its pixels are, so the sizer starts from a table of 114 phones, tablets, laptops and monitors matched to your screen’s size and pixel ratio, an estimate good to about five percent. Laying a coin or a bank card on the glass and matching its outline replaces the estimate with a measurement good to a fraction of a percent, saved for this screen only.
Browser zoom is corrected automatically from the pixel ratio; pinch zoom is flagged, because nothing drawn is true size until it is undone.
pixels per mm = CSS px across the card ÷ 85.60 mm ID-1 card: 85.60 × 53.98 mm (ISO/IEC 7810)