Disposable nitrile, latex and vinyl gloves are labelled XS to XXL, and those letters follow the same hand sizes as EN ISO 21420: 6/XS, 7/S, 8/M, 9/L, 10/XL, 11/XXL (Shield Scientific). ASTM D6319, the US nitrile exam glove standard, then fixes the glove itself: its flat palm width is about XS 70, S 80, M 95, L 110, XL 120 mm, each ± 10 mm.
Why the glove is narrower than you
An exam glove is worn stretched, so its flat width is less than half the hand’s circumference: a medium glove at 95 mm wide lays flat at 190 mm round, for a size 8 hand of 203 mm. Too small and the glove tears at the web of the thumb; too big and the fingertips fold and snag.
Minimum lengths in the D6319 table are 220 mm for XS and S and 230 mm for M to XL; many makers ship every size at 240 mm or more.
glove flat palm width ≈ ½ × hand circumference − stretch hand circumference in inches = EN size
Measure across the palm
The 1:1 sizer measures the flat width across the knuckles and converts it to circumference (× 2.42 for men, × 2.41 for women), or a paper strip gives the circumference directly. Hand-specific surgical gloves come in half sizes from 5.0 to 9.5 on the same inch scale.
Brand cuts differ inside a size: when the sizer lands between two sizes, or on the edge of a band, try both.
Fit, failure and double gloving
A glove that is too small is under tension before work starts: it tears at the thumb web and at the cuff when pulled on, and it tires the hand over a long shift. One that is too big folds at the fingertips and catches on instruments and tape. In a busy clinic or kitchen, the right size cuts glove changes as much as it improves dexterity.
Double gloving for chemotherapy and other hazardous drugs usually takes the outer glove half a size or a size up so the inner one is not compressed; the EN size scale makes that a one-inch step in circumference (size 8 is 203 mm, size 9 is 229 mm).
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)