Conversions (ring sizes, finger sizes, winders, magnifiers, weights)

Which winder do you need for your clock or watch? Which finger / ring sizer?  Which magnifier?  Which weighing scales?  Here are some essential conversion charts. 

Contents

Winders (clock keys)
Winders (watch keys)
Magnifiers: see which magnification / which working distance you need
Weights Conversions, click here

Ring - finger sizes

I 'lifted' the chart, below, from the internet, a simpler and more reliable summary comes from our manufacturer (they export all types to all parts of the world) which goes like this:

UK: A to Z (and extra large sizes go up to Z+6)

USA, Canada, Mexico: sizes 1 to 15 (theoretically down to size 0000...for small babies)

Most of Europe: sizes 1 to 36.

Some parts of Asia: sizes 1 to 33.

UK & IRELAND,  Australia, New Zealand	US Canada, Mexico	INTERNAL CIRCUMF. (mm) Austria, France, Germany (mostly), Belgium, Norway, Sweden, Finland, Russia (usually), Middle East (usually)	INTERNAL CIRCUMF. MINUS 40 (mm) Switzerland, Spain, Netherlands, Italy	INTERNAL DIAMETER (mm) Sometimes used in Germany, Argentina, Russia	FAR EAST Japan, China, Korea, Hong Kong, Taiwan, Singapore
	0	36.5	-3.5	11.6
		37	-3
	1/4	37.2	-2.8	11.8
A	1/2	37.8	-2.2	12
		38	-2	12.1
A½	3/4	38.5	-1.5	12.2
		39	-1
B	1	39.1	-0.9	12.4
B½	1 1/4	39.7	-0.3	12.6	1
C		40	0	12.7
C½	1 3/4	41	1	13.1
D	2	41.7	1.7	13.3	2
		42	2	13.4
D½	2 1/4	42.3	2.3	13.5
E	2 1/2	42.9	2.9	13.7	3
		43	3
E½	2 3/4	43.6	3.6	13.9
F		44	4	14
F½	3	44.2	4.2	14.1	4
G	3 1/4	44.8	4.8	14.3	5
		45	5
G½	3 1/2	45.5	5.5	14.5
H		46	6	14.6	6
	3 3/4	46.1	6.1	14.7
H½	4	46.8	6.8	14.9	7
I		47	7	15
I½	4 1/4	47.4	7.4	15.1
J	4 1/2	48	8	15.3	8
J½	4 3/4	48.7	8.7	15.5
		49	9	15.6	9
	5	49.3	9.3	15.7
K½	5 1/4	50	10	15.9	10
L	5 1/2	50.6	10.6	16.1
L½		51	11	16.2	11
	5 3/4	51.2	11.2	16.3
M	6	51.9	11.9	16.5
		52	12	16.6
M½	6 1/4	52.5	12.5	16.7	12
		53	13	16.9
N	6 1/2	53.1	13.1	16.9	13
N½		53.5	13.5	17
	6 3/4	53.8	13.8	17.1
		54	14	17.2
O	7	54.4	14.4	17.3	14
0½		55	15
	7 1/4	55.1	15.1	17.5
P	7 1/2	55.7	15.7	17.7	15
		56	16	17.8
P½	7 3/4	56.3	16.3	17.9
		56.5	16.5	18	16
Q	8	57	17	18.1
Q½	8 1/4	57.6	17.6	18.3	17
		58	18
R	8 1/2	58.3	18.3	18.5
	8 3/4	58.9	18.9	18.7	18
R½		59	19	18.8
S	9	59.5	19.5	18.9	19
S½	9 1/4	60	20	19.1
	9 1/2	60.8	20.8	19.4
T		61	21		20
T½	9 3/4	61.4	21.4	19.6
		62	22	19.7	21
U	10	62.1	22.1	19.8
10½	10 1/4	62.7	22.7	20	22
		63	23	20.1
V	10 1/2	63.4	23.4	20.2
V½	10 3/4	64	24	20.4	23
W	11	64.6	24.6	20.6	24
		65	25	20.7
W½	11 1/4	65.3	25.3	20.8
X	11 1/2	65.9	25.9	21	25
		66	26
X½	11 3/4	66.6	26.6	21.2	26
		67	27	21.3
Y	12	67.2	27.2	21.4
	12 1/4	67.8	27.8	21.6
Y½		68	28	21.6	27
Z	12 1/2	68.5	28.5	21.8	28
		69	29
Z½	12 3/4	69.1	29.1	22
Z+1	13	69.7	29.7	22.2
		70	30	22.3	29
Z+1 ½	13 1/4	70.4	30.4	22.4
Z+2	13 1/2	71	31	22.6	30
Z+2 ½	13 3/4	71.7	31.7	22.8
		72	32	22.9	31
Z+3	14	72.3	32.3	23
Z+3 ½	14 1/4	72.9	32.9	23.2	32
		73	33
Z+4	14 1/2	73.6	33.6	23.4
Z+4 ½		74	34		33
	14 3/4	74.2	34.2	23.6
Z+5	15	74.8	34.8	23.8
Z+5 ½		75	35	23.9	34
	15 1/4	75.5	35.5	24
		76	36
Z+6	15 1/2	76.1	36.1	24.2
Z+6 ½	15 3/4	76.8	36.8	24.4
		77	37	24.5
Z+7	16	77.4	37.4	24.6
Source for this chart:  https://www.buchkosky.com/education/european_ring_size/ International Ring Size Conversion Chart for Comfort Fit – Hanover Jewelers The Official International Ring Size Conversion Chart (ringsizes.co) International Ring Size Conversion Chart (gessweincanada.com)

 

Winders (clock keys)

We discontinued winders in August 2023. They are now available to special order only, see our article about winders.

(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 square peg that is inside hole, not the hole
- measure any edge of the peg, do not measure it diagonally.

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 longer 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.

 

Winders (watch keys)

We discontinued winders in August 2023. They are now available to special order only, see our article about winders.

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)

 

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

 

Magnifiers: see which magnification / which working distance you need

With any simple magnifying lens, the more powerful the magnification the closer the working distance; the further the working distance the less powerful the magnification.  See our conversion chart: 
Magnifying lenses: focal lengths and magnification converter
(This one is in Excel format, so you might have to click OPEN)

Weights Conversions, click here

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). 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'.

Precious metals are weighed in grams (if they are lightweight) or Troy Ounces (if they are heavy). The one figure you have to remember when weighing gold is: 31.1035g. = 1ozt (or if you deal in very 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

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 either choose a weighing machine that can be switched to Troy ounces or stick to a weighing machine that weighs in grams, find a calculator, divide the grams reading by 31.1035, it takes 2 to 3 seconds!