Method 1: Finger circumference
You'll need:
1. A flexible measuring tape OR a piece of string / a thin strip of paper and a ruler
2. The finger you want to wear the ring on!
Step 1: Place the measuring tape around the finger you want to wear the new ring on to measure the circumference.
Alternatively you can mark string or a strip of paper to the circumference of your finger, and measure that length against a ruler.
Step 2: Refer to the Circumference column in the table below.