Ring Size Converter

Created by Hanna Pamuła, PhD
Reviewed by Małgorzata Koperska, MD and Jack Bowater
Last updated: Jun 05, 2023


Whether you are hunting for the wedding or engagement ring size for your partner, searching for US ring size equivalents, or racking your brain on what's that beautiful ring size in inches, this ring size converter is the ideal tool for you. On the basis of the international ring size chart, we built an intuitive converter that can solve many of your problems. Don't wait any longer; give it a try! If you are curious about how to measure the ring size or how to convert ring diameter in mm into ring circumference in inches, keep scrolling, and you'll find the answer.

How to measure ring size? What is my ring size in mm?

Well, there are many methods to find the proper ring size. For the most obvious and easy one, all you need to have is a string and a ruler.

  1. Wrap the string around your finger. Choose the thickest part of your finger, as the ring must slide over it - it's usually your knuckle. If you don't have a string, you can also use flexible tape, a strip of paper, dental floss, or any other thing that can be easily wrapped around. Don't wrap it too tightly!
  2. Mark the point where the string overlaps.
  3. Measure the length of the string against a ruler - that's our finger circumference.
  4. Here, you can stop the measurements - type the obtained value into the ring size converter. All the other values will be displayed: US ring size, UK ring size, ring diameter in inches and mm... and many, many more.
  5. If you want to find the ring diameter yourself, divide the obtained string length or finger circumference by π (~3.14).
  6. Find the proper ring size - use our converter, chart, or manufacturer website.
ring size measurements.

Also, you can try different methods than this easy, but not so accurate, string-ruler method:

  • Pop into a local jewelry shop - they have more precise tools and stencils to determine your ring circumference, diameter, and finally proper ring size.
  • Use circular sizing printing chart - many online shops provide that solution: simply print out the provided file (make sure that scaling options are turned off!) and match the inside circumference of your ring with the right size of the circle. If you don't have a ring, you need to use a string or paper again.
  • Use online ring sizers - Sometimes jewelry retailers put ring size charts or other sizing tools on their websites. One example of such measurements is the calibration with something of known length (ruler, credit card, SD card, etc.) and then fitting the ring size on its basis.

Ring size guide - useful tips

Whether you are looking for a perfect engagement ring size or original jewelry to complete your look, remember these rules:

  • Different manufacturers can use different conventions. Every time check the jewelry website or ask the shop assistant about the conversion charts or standards they use. Our ring size converter shows the ring size equivalents, which are considered standard, but many, although similar, standards exist. So don't grumble at us if the wedding ring size will not fit perfectly - we warned you. It's the same story as choosing the right clothing size, bra size as is covered in our bra size calculator, or shoe size, which is covered in our shoe size conversion - standard sizes exist, but each manufacturer has their own, which is slightly different from others.

  • Decide in advance which hand and finger the ring is for. Our fingers are not symmetrical, as our whole body isn't as well. Make sure that you measure the exact finger that will wear the ring - even the same fingers on the left and right hand can differ in size.

  • Your finger size changes during the day- it's usually thinner in the morning and wider in the evening, but also it responds to temperature, humidity, and physical activity. Do the measurements at the end of the day, when the fingers are likely to be the largest.

  • Wider rings usually require a bigger ring size. If you are choosing a ring wider than 6 mm, think about a slightly bigger size. In narrower rings, the skin can move to one or to the other side of the ring, but in wider rings, it's not so easy, so the skin stays under the metal, sometimes leaving "ring marks" on your finger.

  • Check the ring size a few times - it has to fit snugly on your finger but can't be too tight. Also, it shouldn't be too loose, as you want to avoid the risk of it falling off. If it's possible, try it on many times, at different times and in various weather conditions. It's especially important to find accurate engagement or wedding ring sizes - you will probably wear them every day, so make sure they fit your finger comfortably.

Ring size chart

To find the ring size equivalents, such as the US ring size or UK ring size, you can use our ring size converter or this shortened version of the ring size chart:

Inside Diameter

Inside Circumference

Sizes

mm

inches

mm

inches

UK & Australia

US & Canada

France

Germany

Japan

Switzerland

11.53

0.454

36.22

1.43

_

0

_

_

_

_

11.95

0.474

37.54

1.49

A

1/2

_

_

_

_

12.37

0.487

38.86

1.53

B

1

_

_

1

_

12.78

0.503

40.15

1.58

C

1 1/2

_

_

_

_

13.21

0.520

41.50

1.63

D

2

41 1/2

13 1/2

2

1 1/2

13.61

0.536

42.76

1.68

E

2 1/2

42 3/4

13 3/4

3

2 3/4

14.05

0.553

44.14

1.74

F

3

44

14

4

4

14.36

0.565

45.11

1.77

G

3 3/8

45 1/4

_

5

5 1/4

14.45

0.569

45.40

1.79

G 1/4

3 1/2<

_

14 1/2

_

_

14.56

0.573

45.74

1.80

G 1/2

3 5/8

_

_

6

_

14.65

0.577

46.02

1.81

H

3 3/4

46 1/2

_

_

6 1/2

14.86

0.585

46.68

1.84

H 1/2

4

_

15

7

_

15.04

0.592

47.25

1.86

I

4 1/4

47 3/4

_

_

7 3/4

15.27

0.601

47.97

1.89

I 1/2

4 1/2

_

15 1/4

8

_

15.40

0.606

48.38

1.90

J

4 5/8

49

15 1/2

_

9

15.70

0.618

49.32

1.94

J 1/2

5

_

15 3/4

9

_

15.80

0.622

49.64

1.95

K

5 1/8

50

_

_

10

16.00

0.630

50.27

1.98

K 1/2

5 3/8

_

10

_

16.10

0.634

50.58

1.99

L

5 1/2

51 3/4

16

_

11 3/4

16.51

0.650

51.87

2.04

M

6

52 3/4

16 1/2

12

12 3/4

16.92

0.666

53.16

2.09

N

6 1/2

54

17

13

14

17.35

0.683

54.51

2.15

O

7

55 1/4

17 1/4

14

15 1/4

17.75

0.699

55.76

2.20

P

7 1/2

56 1/2

17 3/4

15

16 1/2

18.19

0.716

57.15

2.25

Q

8

57 3/4

18

16

17 3/4

18.53

0.729

58.21

2.29

Q 3/4

8 1/2

_

18 1/2

17

_

18.61

0.733

58.47

2.30

R

8 5/8

59

_

_

19

18.89

0.748

59.34

2.35

R 3/4

9

_

19

18

_

19.10

0.752

60.00

2.36

S

9 1/8

60 1/4

_

_

20 1/4

19.41

0.764

60.98

2.40

S 3/4

9 1/2

_

19 1/2

19

_

19.51

0.768

61.29

2.41

T

9 5/8

61 1/2

_

_

21 1/2

19.84

0.781

62.33

2.45

T 1/2

10

_

20

20

_

20.02

0.788

62.89

2.48

U

10 1/4

62 3/4

_

21

22 3/4

20.20

0.797

63.46

2.50

U 1/2

10 1/2

_

20 1/4

22

_

20.32

0.800

63.84

2.51

V

10 5/8

63

_

_

23 3/4

20.68

0.814

64.97

2.56

V 1/2

11

_

20 3/4

23

_

20.76

0.817

65.22

2.57

W

11 1/8

65

_

_

25

21.08

0.830

66.22

2.61

W 3/4

11 1/2

_

21

24

_

21.18

0.834

66.54

2.62

X

11 5/8

66 1/4

_

_

26 1/4

21.49

0.846

67.51

2.66

Y

12

67 1/2

21 1/4

25

27 1/2

21.89

0.862

68.77

2.71

Z

12 1/2

68 3/4

21 3/4

26

28 3/4

22.33

0.879

70.15

2.76

Z+1

13

_

22

27

_

Are you looking for more help in finding sizes? Check out our dress size calculator.

Hanna Pamuła, PhD
Measurements
Inside diameter
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mm
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in
Inside circumference
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mm
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in
Ring size equivalents
US & Canada
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UK & Australia
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France & Russia
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Germany
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Switzerland
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Japan
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