CONVERSIONS

For winders (watch and clock keys), international finger and ring sizes, weights for gold, magnification and focal length

At the bottom of this page is a list of related articles

 

CONTENTS

Ring sizes and finger sizes, international conversions 

Converting clock winder sizes to mm

Converting watch winder sizes to mm

Weights conversions

Magnifying lenses: focal lengths and magnification converter
(This one is in Excel format, so you might have to click OPEN)

Links to conversions for other weights and measures

Ring / finger sizes


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U.S.  Size

Diameter
in Inches

Diameter
in MM

Metric MM
Equivalent

British 

French 

German 

Japanese 

Swiss 

0000

.390

9.91

 

-

 

 

 

 

00

.422

10.72

 

-

 

 

 

 

0

.454

11.53

 

-

 

 

 

 

1/2

.474

11.95

 

A

 

 

 

 

3/4

.482

12.18

 

A 1/2

 

 

 

 

1

.487

12.37

38.9

B

 

 

1

 

1 1/4

-

12.60

39.6

B 1/2

 

 

 

 

1 1/2

.503

12.78

40.2

C

 

 

 

 

1 3/4

-

13.00

40.8

C 1/2

 

 

 

 

2

.520

13.21

41.5

D

41 1/2

13 1/2

2

1 1/2

2 1/4

-

13.41

42.1

D 1/2

-

-

 

 

2 1/2

.536

13.61

42.7

E

42 3/4

13 3/4

3

2 3/4

2 3/4

-

13.83

43.4

E 1/2

-

-

 

 

3

.553

14.05

44.0

F

44

14

4

4

3 1/8

-

14.15

44.3

F 1/2

-

-

 

 

3 1/4

-

14.25

44.6

-

-

-

 

 

3 3/8

-

14.36

44.9

G

45 1/4

-

5

5 1/4

3 1/2

.569

14.45

45.2

-

-

14 1/2

 

 

3 5/8

-

14.56

45.6

 G 1/2

-

 

6

 

3 3/4

-

14.65

45.9

H

46 1/2

 

 

6 1/2

4

.585

14.86

46.5

H 1/2

-

15

7

 

4 1/4

-

15.04

47.1

47 3/4

 

 

7 3/4

4 1/2

.601

15.27

47.8

I 1/2

-

15 1/4

8

 

4 5/8

-

15.40

48.1

J

49

15 1/2

 

9

4 3/4

-

15.53

48.4

-

-

 

 

 

5

.618

15.70

49.0

J 1/2

-

15 3/4

9

 

5 1/8

-

15.80

49.3

K

50

 

 

10

5 1/4

-

15.90

49.6

-

-

 

 

 

5 3/8

-

16.0

50.0

K 1/2

-

 

10

 

5 1/2

.634

16.10

50.3

L

51 3/4

16

 

11 3/4

5 3/4

-

16.30

50.9

-

-

 

 

 

5 7/8

-

16.41

51.3

L 1/2

-

 

 

 

6

.650

16.51

51.5

M

52 3/4

16 1/2

12

12 3/4

6 1/4

-

16.71

52.2

M 1/2

-

 

 

 

6 1/2

.666

16.92

52.8

N

54

17

13

14

7

.683

17.35

54.0

O

55 1/4

17 1/4

14

15 1/4

7 1/4

-

17.45

54.7

O 1/2

-

 

 

 

7 1/2

.699

17.75

55.3

P

56 1/2

17 3/4

15

16 1/2

7 3/4

-

17.97

55.9

P 1/2

-

 

 

 

8

.716

18.19

56.6

Q

57 3/4

18

16

17 3/4

8 1/4

-

18.35

57.2

Q 1/2

-

 

 

 

8 1/2

.732

18.53

57.8

-

-

18 1/2

17

 

8 5/8

-

18.61

58.4

R

59

 

 

19

8 3/4

-

18.69

58.4

-

-

 

 

 

8 7/8

-

18.80

59.0

R 1/2

-

 

 

 

9

.748

18.89

59.1

-

-

19

18

 

9 1/8

-

19.10

59.4

S

60 1/4

 

 

20 1/4

9 1/4

-

19.22

59.7

-

-

 

 

 

9 3/8

-

19.31

60.0

S 1/2

-

 

 

 

9 1/2

.764

19.41

60.3

-

-

19 1/2

19

 

9 5/8

-

19.51

60.6

T

61 1/2

 

 

21 1/2

9 3/4

-

19.62

60.9

-

-

 

 

 

10

.781

19.84

61.6

T 1/2

-

20

20

 

10 1/4

-

20.02

62.2

U

62 3/4

 

21

22 3/4

10 1/2

.797

20.20

62.8

U 1/2

-

20 1/4

22

 

10 5/8

-

20.32

63.1

V

63

 

 

23 3/4

10 3/4

-

20.44

63.5

-

-

 

 

 

11

.814

20.68

64.1

V 1/2

-

20 3/4

23

 

11 1/8

-

20.76

64.3

W

65

 

 

25

11 1/4

-

20.85

64.7

-

-

 

 

 

11 3/8

-

20.94

65.0

W 1/2

-

 

 

 

11 1/2

-

21.08

65.3

-

-

21

24

 

11 5/8

.830

21.18

65.7

X

66 1/4

 

 

26 1/4

11 3/4

-

21.24

66.0

-

-

 

 

 

11 7/8

-

21.30

66.3

X 1/2

-

 

 

 

12

.846

21.49

66.6

Y

67 1/2

21 1/4

25

27 1/2

12 1/4

-

21.69

67.2

Y 1/2

-

 

 

 

12 1/2

.862

21.89

67.9

Z

68 3/4

21 3/4

26

28 3/4

12 3/4

-

22.10

68.5

Z 1/2

-

 

 

 

13

.879

22.33

69.1

-

-

22

27

 


CLOCK KEY CONVERSIONS
(for watch key conversions, scroll down slightly)


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CLOCK KEY CONVERSIONS
(for watch key conversions, scroll down slightly)

If you have a clock and have lost its winder, measure any edge of the square winding peg
(i.e. measure the peg that is inside hole, not hole)

EUROPEAN SIZES

** ORDER THESE SIZES FROM US **

Eur.
000
00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Eur
mm
1.75
2.0
2.25
2.5
2.75
3.0
3.25
3.5
3.75
4.0
4.25
4.5
4.75
5.0
5.25
5.50
5.75
6.00
6.25
6.50
6.75 mm


BRITISH SIZES
(found on antiques keys - this system of numbering is no longe used)

GB
000
00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18 GB
mm
2.00
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6
mm

 

Not sure which size?
Measure the winding peg in mm (millimetres) - all mm are the same
then order the European key size

 

Looking for a radiator key? The butterfly-handle keys give good leverage, used by plumbers when it's stuck:
size 10 fits tightly, but size 11 if it's been painted over.


Buy standard butterfly-handle keys - sizes 00 to 16

Buy Longcase clock winders ("grandfather" keys) - sizes 8 to 16

Buy the largest multi-clock winder - up to size 18

or see all.

 

 

WINDERS (watch keys)

 


BUY NOW: CLICK ON A PICTURE TO BUY

If you have a watch and have lost its winder, measure any edge of the square winding peg
(i.e. measure the peg in the middle of the hole, not the diameter of the hole)

See Watch & Clock Keys (all keys)

 

EUROPEAN KEY NUMBER
SIZE IN MM
BRITISH KEY NUMBER
00
2.00
12
0
1.90
11
1
1.80
10
2
1.75
9
3
1.65
8
4
1.60
7
5
1.50
6
6
1.40
5
7
1.30
4
8
1.20
3
9
1.15
2
10
1.05
1
11
1.00
0
12
0.95
00
 




WEIGHTS CONVERSIONS


BUY NOW: CLICK ON A PICTURE TO SEE SETS OF WEIGHTS
AND ALSO A FULL SELECTION OF INDIVIDUAL WEIGHTS


See weighing machines

See a guide to buying weighing machines

 

Gold and silver is weighed in Troy ounces (ozt).  The Troy ounce, today, is only used for weighing precious metals (it was once used for weighing mail too). Do not confuse the Troy ounce (ozt)  with the Avoirdupois ounce (oz) which is used for weighing food and goods (e.g. kitchen scales and bathroom scales). Manufacturers of weighing machines outside the U.K. sometimes refer to the Avoirdupois ounce as the 'English ounce'. Although there are two different ounces, there is only one 'gram'.

...however... for lightweight items of gold and silver we use grams.  

The one figure you have to remember when weighing gold is: 31.1035g. = 1ozt.
or if you deal in heavy silver items, 32.1507 ozt = 1Kg.

1 TROY OUNCE =
0.911 Avoirdupois oz (ounce) - used for weighing food and goods
31.1035g. (grams) - the gram is THE standard unit of weight, although there is more than one 'ounce', there is only one 'gram'
20dwt. (pennyweight) - the pre-decimal system in the U.K, still used in U.S.A.
480gr. (grains) - used for weighing powder when making up ammunition

TO CONVERT TO GRAMS

Avoirdupois oz = 28.35g.  (exact = 28.349523125g.)
Troy oz (ozt) = 31.103g. (exact = 31.1034768g.)
1lb (pound.) = 453.6g. (exact = 453.59237g.)
ct. (metric carat) = 0.2g.  - used for weighing diamonds
dwt (pennyweight) = 1.56g. (Exact = 1.55517384g.)
gr (grain) = 0.065g. (Exact = 0.06479891g.)
mom (momme) = 3.75g. - Japan, used for weighing pearls
tl (tael) = 37.8g. (Exact = 37.7994g.) - Hong Kong and Singapore

THE METRIC SYSTEM There are two different ounces but there is only one metric system.
For weighing diamonds:100pts (points) = 1ct, 5ct (carat) = 1g.
For all food and goods, and in science:
1000g. = 1Kg.

WEIGHING MACHINES FOR GOLD AND SILVER

All weighing machines (that we sell) weigh in grams.
All weighing machines (that we sell) can be switched to weigh in ounces, but not always Troy ounces.
If you want to weigh in Troy ounces, choose a weighing machine that can be swithed to Troy ounces (they are a little more expensive)
or stick to a weighing machine that weighs in grams, find a calcualtor, divide the grams reading by 31.1035, it takes 2 to 3 seconds!

 

CONVERT ANY UNIT OF WEIGHT TO ANY OTHER UNIT OF WEIGHT

If you are converting weight to calculate the price of gold (priced in U.S. Dollars per Troy ounce of pure, 24ct, gold):

 

CURRENCY CONVERTER

 

RELATED ARTICLES (jewellery and horology)

Conversions (clock and watch key winders) - illustrated.

Measuring diamonds

Cleaning, polishing and polishes

Screws and screwdrivers

Styles of jewellers pliers and cutters

Removing tarnish from silver

Ultrasonic cleaning machines

 

 

QUICKTEST, Watford, WD18 8PH, Tel. 01923 220206, email info(at)quicktest.co.uk