HOW TO CHOOSE THE DIAMETER OF A CLOSED ROUND BRACELET?

To know your size, measure with a tape measure the turn of your hand to the widest with your thumb curled up (as if to put on the rush) ...

mesure poignet jonc

And refer to the following grid:
If needed cm to inch, follow this link :
CM TO INCH CHART

Circumference Wrist measured Diameter of the ring to choose
17cm 55 mm
17.5 cm 56 mm
17.8 cm 57 mm
18 cm 58 mm
18.5 cm 59 mm
19 cm 60 mm
19.2 cm 61 mm
19.5 cm 62 mm
19.7 cm 63 mm
20 cm 64 mm
20.5 cm 65 mm
20.8 cm 66 mm
21 cm 67 mm
21.3 cm 68 mm
21.6 cm 69 mm
22 cm 70 mm
22.3 cm 71 mm
22.7 cm 72 mm
23 cm 73 mm
23.2 cm 74 mm
23.5 cm 75 mm
23.8 cm 76 mm
24.2 cm 77 mm
24.5 cm 78 mm
24.8 cm 79 mm
25 cm 80 mm
25.4 cm 81 mm
25.7 cm 82 mm
26 cm 83 mm
26.5 cm 84 mm
27 cm 85 mm

For kids :
1-3 ans = 43 mm
3-4 ans = 45 mm
4-5 ans = 48 mm
5-7 ans = 50 mm
6-8 ans = 53 mm
9-11 ans = 55 mm
12-14 ans = 58 mm