Methods
Using a flexible tape measure
Place a flexible tape measure around your neck. To find your necklace size, meet the ends of the measure where you would like the pendant to fall on your chest (as pictured above), and note the length.
Measure full length
Lay the necklace on a flat surface in a straight line. Using a ruler or tape measure, measure it from one end of the clasp to the other.
Measuring when fastened