Are you uncertain of your ring size? You can easily find it by measuring one of your rings, as shown in the picture below.

1. Measure the inner diameter in mm.

2. Calculate your ring size using this formula:
<Inner diameter> x 3,14 = your ring size

You have measured the inner diameter to 17, 1 mm
17,1 x 3,14 = 53,7
Your ring size is therefore 54.

If you do not have a ring that fits, I recommend that you swing by a goldsmith or jewellery store and have your finger measured to get the accurate size.