The reliable way to determine ring size is to measure the circumference of the knuckle base in millimeters, then convert that number into US, Chinese or EU sizes. Measure in the late afternoon, when the hand is warm and dry, and take three readings to average out swelling from heat or cold.

1. Home Measurement Method

Wrap a non-stretching string or narrow paper strip around the base of the finger, mark where it overlaps, then straighten it and read the length in millimeters on a ruler. Alternatively, measure the inner diameter of a ring that already fits you comfortably. Remember that the knuckle is usually wider than the finger base; the ring should slide over the knuckle but not slip off. Do not measure right after exercise, a hot bath, or on a very cold day, because finger circumference can shift by half a size or more during the normal day.

2. US, China and EU Size Conversion

• Chinese or HK sizes: around 47 mm circumference equals size 7, around 56 mm equals size 14, with roughly 2.3 mm between each size.
• US sizes: around 49.3 mm equals US 4, around 59.5 mm equals US 8, with most adults wearing US 5 to US 9.
• EU sizes: marked directly by circumference in millimeters, so 49 equals EU 49 and 59 equals EU 59.

Quick reference: Chinese size 10 is close to US 6 and EU 52; Chinese size 13 is close to US 7.5 and EU 55; Chinese size 16 is close to US 9 and EU 59. When buying cross-border, trust the millimeter circumference rather than the number printed on the band.

3. Buying Tips

• Wide bands fit tighter, so choose half a size up for bold rings.
• Adjustable bands skip measurement but fit less securely than fixed sizes.
• Rings feel tighter in winter and looser in summer, so measure at room temperature.
• If the knuckle is large, prefer styles that can be gently resized later.

MASCOT Jewelry supplies 925 sterling silver bands that can be produced to a client circumference or resized, and OEM and ODM orders can be marked with the target US or Chinese size for export to more than 50 countries.