The best, most accurate way to find your ring size is to go to your local jeweller and have your finger measured professionally or head to Amazon and buy a cheap plastic ring sizer. However, if you are unable to do this, follow the guide below.
To find your ring size you can use a piece of string (for 1.5mm stacking rings) or a piece of paper cut to the same width as the ring band you are after. Wrap the paper/ string around your finger and mark with a sharp pencil where it begins to over lap. Measure the length to the nearest half millimeter. It is very important to be as accurate as possible with the measurement!!