Your fingers might also swell if you're pregnant or taking certain medications. Take this into account when measuring your fingers.
It is suggested that you measure warm fingers at the end of the day to ensure they are at their largest, or most swollen.
Between two sizes, choose the one above.
Here are 2 methods to find out your ring size
Using a Ring charts
1) Download and print the charts here ( Be sure your page scaling is set to "none.") the chart will show a number of circles of different sizes.
1) Locate a circular ring sizing chart. Most reputable online jewelry retailers offer printable charts. The chart will show a number of circles of different sizes.In order to ensure that the size chart is not distorted in printing, many sites will ask that you place a penny on a printed penny icon to check that scaling is accurate.
3) Find a ring you would like to size. Choose a ring that fits snugly, but not tight. As every finger on each hand is a slightly different size, the ring you choose should be for the intended finger.
Using Paper or String
1) Cut a strip of paper or a piece of string. The paper strip should be approximately 1/2" wide, and 5" long.
2) Wrap the paper or string around the finger to be sized. Slide the paper or string up to the knuckle, as the ring must be sized large enough to able to slip off and on, over the knuckle.
3) Use a pen to mark the string or paper where the long end overlaps.
4) Measure the mark from the end of the length of paper or string with a ruler.Use the metric side for more accurate sizing.
5) Then locate your ring size by locating your measurement you can download the ring size chart here