Insidediameter

Insidecircumference

Insidediameter

Insidecircumference

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Ring size chart

Calculating ring blank lengthTo determine the length of a metal blank needed to make a ring, you need to know the inside diameter of the desired ring size, the gauge (thickness of the metal), and the width of the metal.

For bands up to 4 mm wide, and between 24 gauge (0.5 mm) and 12 gauge (2.1 mm), you can use the following formula to calculate the ring blank length:

Ring blank length (mm) = inside diameter (mm) + metal thickness (mm) x 3.14

For bands wider than 4 mm, add 0.5 mm to the length of the blank.

US SIZE UK SIZEINSIDE DIAMETER (MM)

INSIDE CIRCUMFERENCE (MM)

5 J 15.6 49

5 ½ K 16 50.3

6 L 16.4 51.5

6 ½ M 16.8 52.8

7 N 17.2 54

7 ½ O 17.6 55.3

8 P 18 56.6

8 ½ Q 18.4 57.8

9 R 18.8 59.1

9 ½ S 19.2 60.3

10 T 19.6 61.6

10 ½ U 20 62.8

11 V 20.4 64.1

11 ½ W 20.8 65.3

12 X 21.2 66.6

12 ½ Y 21.6 67.9

13 Z 22 69.1

Ring mandrels