When measuring your wrist, stay as close to your hand as possible, like so 
(the circumference in the photo is 7.25 inches / 18.4 centimeters.)
Don't have a measuring tape?
Use a piece of string to measure your wrist and lay the string back out on a ruler to get your measurement in inches or centimeters.

When ordering

Please specify the exact number on the measuring tape and whether you prefer your bracelet a little looser or tighter.
Gift guide
When surprising someone with a gift, we completely understand that measuring their wrist isn't an option, as it would ruin the surprise. So perhaps the following general overview of sizes could be of assistance:

Wrist measurement
(in inches)
 Wrist measurement
(in centimeters)
5.5" 14 cm  XX-Small
6" 15.2 cm X- Small
6.5" 16.5 cm Small
7" 17.8 cm Medium
7.5" 19.1 cm Large
8" 20.3 cm X-Large
8.5" 21.6 cm XX-Large
9" 22.9 cm XXX-Large