You can determine the correct ring size with three different methods. Method number 1 is to measure your own ring, number 2 is to measure your finger and the last, number 3, is to measure your ring size with a measuring instrument.
METHOD # 1
Take your own ring and measure the diameter of the inside of your ring with a ruler.
If your ring is for an example 19 mm in diameter - your ring size is 19.
METHOD # 2
Use a measuring tape to measure the circumference of your finger. If you don't have a measuring tape, use a thin piece of paper or string and then measure the length of it with a ruler. This is the circumference of your finger. See the ring chart below to know your size.
METHOD # 3
Measure your ring size with a ring meter.
RING SIZE CHART